I have 2 steam installations, one for the dev-branch of arma3 and one for the stable version. In the directory ,you mentioned ( C:\Users\<username>\AppData\Local\Arma 3) seems to be only rpt files from the stable version (calculated on the dates of writing the rpt files), which does the job.
Is there another place, where i can look for the requested rpt files of the dev branch?
Should I start the game with special commandline options, to provide you with more useful dumps or debug informations?