Originally Posted by
JoeTBM
If it is a Schrader, remove the valve core and check it, especially if the tube had slime in it. We have replaced quite a few cores later for being "clogged" as they were not fillable.
Good advice as the sealant is stupid. It sees the valve as a big hole to clog in

We see clogged valves with old sealant filled tubes regularly. Andy