Pot repro:
/setblock ~ ~ ~1 minecraft:decorated_pot
/setblock ~ ~ ~1 minecraft:decorated_pot{sherds:[angler_pottery_sherd,angler_pottery_sherd,angler_pottery_sherd,angler_pottery_sherd]}
Pot is still blank
/data get block ~ ~ ~1
Shows the data
Relog -> data now gone

Head repro:
/setblock ~ ~ ~1 minecraft:player_head
/setblock ~ ~ ~1 minecraft:player_head{profile:slicedlime}
Head still default texture
/data get block ~ ~ ~1
Shows the data
Relog -> head now correct (possibly because the async data get dirty marks the block entity properly?)