Here I was doing the normal Platesolving when things started to go a bit wrong and Platesolving (any type - ASTAP,Astrometry local etc) starting failing - some weird errors and even core dumps from segmentation failures.
Anyway after pulling all of the little hair left out I found the problem - on 1 Index Platesolving gave some saying "Invalid Star ID" - trouble is unless you scroll through the whole log you wouldn't necessarily see it as you get the segmentation fault or iotclt fault info. It appears the index had become corrupted ( I did have a lock up once - but reading ! ) so replacing that single index cured the problem.
Still perplexed / worried why reading should corrupt files on a newish SSD .
So if you have a weird set of errors (think I had error 139 and error 256) and /or segmentation fault / core dumps when running platesolving - check the log closely for any "Invalid ID" it might help