I am using a Balance 310X in Drop-in Mode configuration, fully functional with version 8.4.1 build 5791, after updating to 8.5.0 build 5884 there is no longer a connection to the internet as if there is no Drop-in Mode function .
Reinstalling 8.4.1 everything worked again.
I do a quick check and I do see the Drop in mode option after upgrade my device using 8.5.0 firmware.
if you still see the issue, can you create a ticket here for support team to check ?