"This Album is Empty" after rearranging HDR stack in album

Hello,

After moving one or more stacks to a new location within an album I immediately get a "This Album is Empty" error message. Using command-Z to undo the move displays that the undo has taken place, but the album remains empty. Restarting Lr doesn't help. Pretty strange issue and haven't found a workaround besides making a new album which is obviously not really a long term fix. Appreciate any help!