Just posting this again after downloading the test branch, and this being still an issue.
I cannot place more than 1000 decorations. Once I reach that number, at random other decorations will disappear. This can be observed with the counter next to already placed objects and the general one in the upper-left corner.
I tried it a few times, and sometimes, it only really took effect after I saved my game, closed it, and then reopened it. Meaning while I decorated, everything looked fine, but once I closed the game, things disappeared and the decoration number was a clean 1000.
Still requesting this to be fixed please.