The WPFTS Pro version you are using is very outdated. Please consider upgrading to 2.46.x which is the latest. It has a completely new indexing and searching algorithm and it should solve your issue.
Never ending Indexing
we have manually restarted the indexing process on our website and now the process is running endlessly and has stopped at exactly 18%.
We have about 8000 items and the process always stops running around 1500.
We thought it was the cron but it is manual and runs every 5 minutes.
What exactly can be the problem here?