At a point I "crafted" lamps until my inventory was full, then clicked on one of the lamps to have it go on the cursor, then I pressed q to clear the cursor, and got the "cannot insert x, player's inventory is full" message. I guess it's technically right since the slot is now occupied by the hand "placeholder?" (not sure how to call it) but it's still unexpected behavior: expected result would be to have the cursor free and the stack of lamps currently on the cursor to to go in the inventory replacing the hand placeholder after pressing q.
(screenshot taken just after pressing q)

Other weird behavior includes being able to swap the currently on cursor item with another one in the inventory, the inventory will auto sort but keep the hand placeholder in the same inventory slot, expected would be to have the hand placeholder in the slot that I just took the new item from, or the slot just before that one since the inventory after the old hand placeholder moves back one slot from the old hand placeholder moving.
(from the situation in the previous screenshot I clicked on the iron gear wheel)

Now this might be unrelated but seems to be too close to this one: If I put the item on the cursor in an inventory with ctrl+click (again sandbox scenario) the cursor will have the next stack of that item in it, while the hand placeholder would not appear in the inventory, expected would be to still have an hand placeholder occupied slot in the inventory since the cursor is still holding an item.
Seems very close since both are showing pre .17 inventory behavior in the sandbox scenario.
(from the previos screenshot I ctrl+clicked on of the chests to put the iron gear wheel in it)

I used commands to give me the dev accumulator for infinite power and infinty chest, but I don't think that's related to the issue.