I have a problem with QGIS 3.6.0 on macos and QGIS3.2.3 on Windows7 with running processing scripts and models in background. According to QGIS3 docs they are run in background thread by default (if there is no FlagNoThreading flag defined.
Unfortunately there is no "run in background" button on processing dialog (just "Run") and they are run in main GUI thread (or in other thread but blocking GUI anyway).
I couldn't find any QGIS configuration setting for this. What could be the reason for QGIS3 to run them in GUI-blocking mode?