Build allays can become 'trapped' in ramps if the ramp is too steep. The allay sits on the stairs and does not return to the player's allay inventory. Issue MCLG-103 "Build Allays stuck on 0 despite them not being in use" is possibly a result of trapped build allays.

Deconstructing the ramp frees the allay to return to the player's inventory.

See video for example.