When a panda rolls, if it rolls into the corner of a fence, the panda can become permanently stuck there unless pushed out by the player or another mob. The hitbox is not overlapping with the block (see screenshot), but the panda cannot pathfind out of the corner, even if tempted with bamboo (see screenshot). There is nothing impeding its movement but it cannot pathfind anywhere.

This only seems to occur in pandas that roll.

Apparently this can also occur with walls and fence gates, as described by MC-156435, but this bug report was marked incomplete.