I'm not to sure how this one occurs, but some time during game play (strategic level) your laboratory space will be used by a "phantom project"
That is, you have have 30/30 scientists (available/all), but you would have 9/30 (used/total) laboratory space
The only way to get rid of this bug (that I've found) is to complete all outstanding research projects that the base was ALREADY researching, then un-hire all the scientists, then destroy all the laboratories, then rebuild + rehire.
You can also produce a bug message (Assertion error) by doing the following
Suppose this problem is occurring at Base1. If you go to another base (Base2) and then set its research projects to 0 scientists.
{Minor bug here, even with 0 scientists it will say its still being researched, I think this is where the laboratory space goes to}
Any way, with its 0 scientists left, it still says its researching so you press the stop research button, then you try assigning more scientists from Base2, to the now un-researched projects (previously from Base1), and this produces the assertion error.
Althought I believe that fixing the initial problem would probably remove the cirumstances for this second issue all together