No, you are a victim of the RNG conspiring against you. Zone (loading screen) to another place and check the crew skill list again. You are however at the mercy of the Diplomacy Mission Distributions (thanks to Bioware making changes in 1.2).

Ok, updated the UWT mission distribution list. It now covers grades 2-6. Each grade dedicates at least 50% of the missions to Gifts. The remain portions are split between Fabric & Metal.

This is the snapshot for what Grades 2 & 3 look like so far.

As you know, just one snap shot does not paint an accurate picture. This is what I know about the distributions so far. I think I'll try to nail down the grade 2 & 3 missions too.

Do a little more research. That is not the case. Bioware changed the available mix of missions based on the flavor text alone (so it didn't look like you were assisting the opposing faction). Take a look at Diplomacy Problems in 1.2 for a full rundown on the mission mix per faction for each grade. To the OP: There are a few things you can do to improve your chances at getting the Medical Missions you desire. 1.) Do the relog or jump on/off your ship to get the list re-randomized. 2.) Run any number of available medial missions in the Grade you desire. About 20 seconds before it completes, Have all of the rest of your companions run every single remaining mission in that Grade (gift or medical, doesn't matter). When the original completes, the five missions in that Grade will get re-randomized minus the ones you just shotgunned. This will increase your probability of getting missions you want. If there are now more than one of the missions available that you desire to run, run the mission with your original companion and one by one cancel your other companions and send them on the ones you want. Then cancel the rest of the undesired missions (you get a full refund upon cancellation). 3.) Realize that you are forever hosed because Bioware decided your faction did not deserve access to Rich (and in some cases Bountiful) Medical Supply missions. Level an alt on the opposing faction and re-level Diplomacy. That way you have full access to Rich medical supply missions at every Grade. 4.) File an in-game bug and post a complaint on the support forums. 5.) Bow to the whims of the GTN gods and hope that you can find what you want and have enough credits to buy it.

Just added to your list.

If this is now the "official" UWT discussion thread, what more needs to be discussed? We already have a rough idea of the mission distributions for a few of the grade tiers. We know that the mechanism for populating the five missions in the Crew Skill window is pretty random. We know that there are tedious ways to circumvent the randomness (ship hopping or staggered companion missions to narrow the pool of possible missions). People have discussed ways to broaden the the draw on resources provided by UWT so that there is a demand for Fabric. There have also been suggestions to place more control in the hands of the user so they can select which types of missions they want to have their companions tackle (to avoid the randomness of populating the crew skill window with missions). And yet another suggestion is to have at least one of each type of mission (per loot type) available in the Crew Skill window for each graded tier each time it gets populated. What more do you need to hear from your user base Bioware?

You must really love that BW decided to help LS/DS rp angst by denying you access to missions based on mission flavor text. "Diplomacy missions that previously indicated the player was assisting the other faction are now appropriately faction-restricted."

Yes, there is in fact a reason. When 1.2 rolled out, Bioware decided that you (being an Imperial) did not deserve to have access to certain missions solely due to the mission flavor text. So in essence, if you want a semi-reliable source of Diplomacy mats you will need to level a character on both factions and raise Diplomacy on those two (or more) characters. Enjoy! Beyond the fact that Bioware is conspiring against you, the mechanism used to populate the mission queue with five missions is completely random. The problem is that the pool of available missions is stacked against you. Take a look at what you are up against (if you don't feel like following the link above). The Grade 4 rich medical supplies missions are hiding over on the Republic side. The following are the Grade 4 Diplomacy missions for both Imperial and Republic factions. The missions unique to Imperial players will be highlighted in orange, Republic in blue. Yay more data.

From the UWT mission distribution list (still valid for 1.3). What Bioware needs to do is remove a few Gift missions from the mix (not add more metal) to allow more randomizer hits on Metal missions.

My crew have found a fair percentage of purple metal mats in 1.3 so far. The only thing you can do is document your results to verify your claims. Saying that some guy on General chat said something is meaningless. Put yourself in the best position to succeed. Max affection on your companions, use a companion that has +crit for UWT. If all else fails, try using a Mission Discovery. There is no secret voodoo to how the missions get populated in the Crew skill window. Take a look at the Underworld Trading mission distributions and you'll understand it better. It is all just a random generation based on the lists. The problem is that there is an overabundance of Gift missions. There is no 'rich' Grade 6 metal mission. It was mislabeled as rich and Bioware corrected the text when 1.2 rolled out. The yield has been the same.

The separation of medical supply missions to each faction based on flavor text is still a problem in 1.3

Do a little digging

I don't think they use anything other than a RNG to populate the list. The problem is that the pool of missions are diluted. UWT mIssion Distribution

Take a look at this Underworld Trading Mission Distribution to get a better idea of what you are up against. I'm not sure if the mission mix is the same for the Republic side, but I wouldn't put it past BW to do something stupid like that.