Thanks. I tried those symbols and the response is different. For example for "ULVR-STK-LSE-GBP":
"!No security definition has been found for the request ULVR-STK-0.00-LSE-GBP
Error 053: ULVR-STK-LSE-GBP unavailable at this time"

I confirmed I have LSE market data subscription, but no joy. It shows in TWS so I think the IB side is OK.

Also get thes same error for Euro exchange such as "DTE-STK-SMART/-EUR" (Deutsche Telekom).