I ran into this bug too. Wish I had read this thread before wasting millions in resources.

Still broken, logging or travelling to stronghold resets the tunnel entrance.

Got one! Last night, after 5 more attempts, I got a grade 8 crit. Whew, for two weeks I though I was doing something wrong.

Yes, I've been doing Disassembly Required. I've done 3 or 4 per day, so somewhere around 45 missions completed so far with only the blue grade 8 part (biocell memory core).

After two weeks of KOTFE, I haven't been able to crit a single rich slicing mission. I've got my companion up to influence rank 30, so I'm lead to believe that I now get +15% crew skill critical. I send him out on grade 8 rich missions, and have only received blue grade 8 parts. What am I doing wrong, or what should I be doing? If my math and underlying assumptions are right, I should be getting 15 crits for every 100 rich attempts. I realize it's a crap shoot every time, but over a large enough sample, 15% should equal 15%. I may need to try 10,000 times to get one crit, but that is more like 0.01%.