Qt 5.15.0 since image conversion is using global thread leading to dead lock in some situation where large number of image files are being read and QFuture and watchers are being used to parallelize it.
Attached example can be used to reproduce it on windows, this works good with 5.14
Mostlikerly this change is the reason of it:
|For Gerrit Dashboard: QTBUG-84619|
|302569,3||Do not multithread if already in a global threadpool thread||dev||qt/qtbase||Status: MERGED||+2||0|
|302780,2||Do not multithread if already in a global threadpool thread||5.15||qt/qtbase||Status: MERGED||+2||0|