Odd problem with vents

I've been having a sporadic problem with air vents, specifically when depressurising.

Working airlock vents stop sucking up air occasionally. However once it happens the only way to fix it is to completely rebuild the grid (or cut/pasta in creative).

Not a major issue as I try to be careful with airlocks but a bit annoying all the same.

If anyone else is having this issue or knows a work around, I'd love to hear from you.
Thanks

 

If your O2 Tank your vent is connected to gets full it will stop decompressing fully. You will have to "bleed off" excess O2 from your tank.

 

I checked that, tank was 12% full and connection was intact and operational.