I haven't boiled it down fully but the mining turtle disappears when you relog, and was able to fix it but installing the version 1.100.6 instead of latest. No mention of this on CC:restitched github so it may be special to this modpack but I did find a mention of chunk not saving when there is a computer placed which might be related. It does not disappear from the inventory.

In singleplayer only CC blocks always cause chunk save failures, you mention using a different version fixes it? That may help us, as the devs have stated they weren't going to backport this fix...

I have not had any issues since, but to add to this I had some of my items disappear from my inventory which may be caused by failed saving.

And turtles can mine diamonds, and can't find any way to equip an Iron pickaxe onto a turtle unlike whats said in quest book.

b8d806d