Inconsistent Drain

[Prange]

I replaced a wall-mount bathroom sink a few weeks ago. Everything is in the same location as the old one.

It drained fine when installed. Now it didn't drain for me once a week later. Then it did. It happened again today. Now it's fine.

It's in the powder room and not used often.

Any thoughts on this? Thanks.

 

[hj]

Usually, it is caused by the drain's "pop up" unit not lifting high enough, along with an obstructed, or nonexistent overflow passage.