I'm using the search function for inactive Pathfinder games, but every time I hit the Next 25, I get nowhere - it keeps repeating the first 25.

It says there are only 25 such games, period. The 25th was last active in 2022, so that may be accurate.

Yup, we have identified a bug with search on inactive/deleted games and we've referred the issue on to jase to take a look at when he gets a moment in his busy schedule (along with all the other things on his perpetual to-do list).  :>