Dropper post wont take air

After heavy googling on the issue, I couldn’t find anything that was the same as my issue. I’ve had this dropper post for some time now (A DNM asp) and recently I went to top up its air as it was returning a bit slow, however, when trying to connect my shock pump to the valve, no air would go in, instead, the air would be getting bottled up in the valve area. The pump, to my knowledge, is not leaking any air. I’ve also tried pushing down the pin to release a bit of air but no hope there either. I also have tried using other pumps to no avail.

Any help is appreciated,

Thank you