When attempting to gather a digital miner using a sapphire pick that was on its last use(0/whatever durability), the pick breaks and the digital miner vanishes..doesn't drop an item or go in to inventory.
Issue occurred in Bevo's Techpack using minecraft 7.10, the sapphire pick I was using is from ProjectRed-Exploration, the digital miner did have inventory in it.(not sure if this will help, just trying to be as specific as possible)

I tested it in creative and it appears to do the same with a gold and iron pick as well...and happens with any mekanism block but not with blocks from other mods. This could be on purpose, but I thought I'd report it anyway.

First, the digital miner keeps it's inventory when picked up so that shouldn't affect it vanishing or not.
The pickaxe's durability shouldn't affect that either, the pickaxe will just break.

As for the testing in creative, you do know that in creative blocks you pick up/break vanish completely and don't create an entity that can be picked up (I guess you know that just trying to rule out every possibility)

Did you try picking up the mekanism blocks with a wrench? It is faster overall, more precise and actually the way it is intended, I do remember that some blocks seem to vanish if broken with a tool and not dismantled with a wrench.

I hope I could help you, keep me informed as to what you found out. :)

By creative I mean I spawned in a bunch of mekanism items on my creative world, wore down some picks, and tested them while in survival mode
I'm aware that it is meant to be picked up by a wrench, but the items do not vanish until the pick breaks, and it only appears to be happening with mekanism so I thought I'd point it out. :)

In addition to that: Accidently right-clicked with a Bound Pickaxe from Blood Magic (Clears cube around player), the Machines vanished. Pipes and Cables pop off normally.
Playing on BTP 10.5.

This has to do with the way Mekanism machines are dropped - they aren't considered "dropped items" by the game, instead I manually have the entity dropped when the block is harvested. As from the first issue in regards to the worn out pickaxe, I can't reproduce it on my end which makes me think it's an issue with another mod hooking into that event.