When swapping sets, you cant see items in bag.
When you select "show bags" you can see the items. And then turning off "show bags" you can then see the items again.

Using version 0.1.21 of Betterbags and 1.4.0 of BetterbagsItemrack and itemrack-classic 3.77.

This seems to be a problem on the end of BetterBags.
At the time of swapping gear this, addon does not interfere with what happens inside the bags.