Pretranslate task

Hi,

I use Trados Studio 2021 SR1 - 16.1.8.4404.
If I let execute a pretranslate task like 

AutomaticTask pretranslateTask = fileP.RunAutomaticTask(
guids.ToArray(),
AutomaticTaskTemplateIds.PreTranslateFiles);

and some server or file based translation memories are linked with the project, I often get "Unexpected exception when configuring file multiFileConverter for task 'Pretranslate'" exceptions and that a TM couldn't be instantiated. If I start this task with only one sdlxliff file at the same time then everything is fine. Why are there problems with parallel execution?

Kind regards,
Andreas Meisel