I am trying to place a lot of solar panel VIIIs on my base and throw in a bunch of upgrades to them, but often times after I do that, close the world, then reopen it, the upgrades will go missing from the solar panels. Worse than that, they aren't returned to my inventory - it's almost as though they've just disappeared entirely.

Screenshot after adding the Transfer Rate & Efficiency upgrades:

Screenshot after closing & reopening the world after adding those 2 upgrades: