Hi Brian,
A few times, I've had an order rejected by IBKR due to puzzling margin requirements. Apparently some securities are deemed non-marginable, and the only way I've found to know this status beforehand is by manually looking up the asset at contract.ibkr.info and looking at the "Margin Requirements" section (which will say '100' instead of 'Default' for 'Short Margin'). For examples, you can search for 'MRNA' or 'NVAX'.
Is there a way that QuantRocket can get this info programatically? I've looked through the IBKR fields in the Securities Master, but nothing about margin rate. Any way to send a request for this info via their API?