Our site experiences the same problem. With, or without "Allow quick checkout" enabled.
We use DeepL.A workaround, is to go into the tmgmt_job table, find the most recent job item.
The `translator` column would be NULL for that job.Change it to `deepl_pro` manually. (On production. Yes, I too like to live dangerously).
Go to the Job overview, and resubmit the job.Patch #19 fixes it for us, but is as berdir mentions maybe not the correct fix.
The problem is probably that upon creation of the job, the translator is not being set correctly.