Collapsing Adjustment blocks within tabs

I created a custom tab, to include the adjustments I use frequently. I keep about half ot the "blocks" or functions open for easy access, and about half closed/collapsed (those I only need occasionally, and I don't want them taking up space).

The Adjustment blocks frequently collapse on their own, requiring that I simply go the arrow on the left and reopen it. What causes these blocks (ie, Exposure is one "block") to close on their own? (am using 4.5.229)