@KRISMA,
When I tunnelled into an iron ore vein I had sand and couple ore blocks collapse. Only collapsed about 6 high then it stopped, even though there was more sand/ore up to the surface (another 30 blocks).
Went into godmode, took a side on screen shot and filed a bug report (b208). I think there were a couple reports filed for earlier experimentals, but it's not on the Known list and so far my report hasn't had a tester add a comment.
https://7daystodie.com/forums/showthread.php?96766-Alpha-17-Experimental-B208-bug-reporting-thread&p=890268&viewfull=1#post890268
Haven't had any cave ins in Stone. Though largest unsupported I've mined is a 5x7 room.
---
XP pop-up icon.
For right now I like it; let's me see that the Biker/VaCa-Cop are worth 1200 but Edgar & Fat Mama are only worth base 700. See how much xp for upgrading or mining, etc.
But I'd also prefer far fewer knock-downs. Then, if XP popup goes away, then the rarer knockdown could be a faker and a nasty suprise. Though to be fair I have noticed that the machete rarely knocks em down.
Long term, once the 'xp per X' is stabilized it could go away. Though a toggle would be nice.