Female quick fill adapter leaking…

My female quick fill foster fitting recently has been acting up, wont take seat/seal when connected to the male quick fill connectors. Mechanical connection is good, though now most of the time it doesn’t make the air tight seal it should or did as new. 75-90% of the time it just leaks out between the connectors whnt he scuba valve is cracked. Tried opening quickly and full open in hopes that a quick or hard blast of air would “seat” the O-ring that approach has not worked at all. Disconnect and reconnect the fittings works only sometimes. When it does work it starts out leaking and then “pop” as if the O-ring takes it seat and the gun fills normal and the connection doesn’t leak at all during the fill. Disconnect procedure is close the scuba tank valve, then open the bleed valve till all air is purged from the line, then disconnect the fitting.
Tried a dab of divers silicone paste on the O-ring in the female fitting, no change. The O-ring visually looks great, no nicks or scrapes or deformation that can be seen on the visible portion, and as mentioned, when it does seal it is seals 100% no leaks, most of ht time it doesn’t seal at all now.
It as bought new back in Late Oct-early Nov, used on 3 different male fittings.

Any ideas, help etc? Have stopped shooting till resolved as it is wasting LOTS of air trying to get my 3 PCPC’s filled.

TIA,
Paul