Unsure if this one has been found and posted, or if anyone else is experiencing it:
If you drop a THMPR close to an enemy on an angled surface, it has a chance to ricochet and fly off in a random direction, either colliding with terrain and becoming clipped, or stopping after a second or so
This sometimes causes the THMPR to skip its "power up" animation, other times the THMPR will continue the animation as it ricochets
Afterward the THMPR will either remain motionless or behave "normally" , it does appear to want to walk back to its original location called down before mining but will need to confirm
If the THMPR is in its motionless state, then regardless of how far it was thrown, it registers the original target spot as the location of the THMPR, not its current location
The "skipping" and "motionless" appears to occur more when the THMPR becomes clipped, or skips its animation. I've been more succesful causing the ricochet when attempting to drop ontop of enemies, and yet to have it go off on just an angled surface
I was able to get it to occur several times , I will attempt to record a couple of examples and upload on here.
Update #1: This also appears to happen if the enemy is also on a "flat" surface
Update #2: The only appears to work on Tsi-Hu , in order for the ricochet to occur you need to partially clip a object with the THMPR as it comes down. Most terrain will not allow you to call a THMPR down on it, even if the target is green. However if you aim the drop from the back of the Tsi-Hu you can cover it with most of the target reticle and still call the THMPR down
Update #3: small video i made to showcase some of the things i've seen