In version 840 I tried to fix a persistent bug in X-Plane where objects sometimes randomly disappear…turns out I got the math wrong.
The next 840 beta (which I think will be called “RC1”, but I am a poor predictor of these things) has a bug fix to the bug fix. I don’t know how many of these bugs this will fix (some appear to be due to driver issues) but I think we’ll be closer.