SQL Questions in Embedded Dashboards with Locked Parameters

So, I'm able to embed dashboards with locked parameters to show only the right data to the right people. We love it, with one outstanding problem:

"Regular" questions are working well, but I can't make it work with questions that are defined in SQL (where it says "This question is written in SQL") show up.

I can connect them to the form filter on the non-embedded dashboard and they work just fine, but the moment I go to embed (Embed this dashboard in an application) the native questions work while the SQL ones do not. I get the "There was a problem displaying this chart" message.

I've tried both native and field filters. I've tried making them required or optional. I've experimented with a bunch of permutations involving square and curly brackets, but nothing seems to work.

Running Metabase v0.37.4 on Linux, my database is MySQL on AWS RDS.

Hi @MartinCron
Check Admin > Troubleshooting > Logs for more details.
Latest release is 0.39.1