CLI Telnet conflct with SSL on other port?

I don’t know if this is something I did in my app (I think not though), or an issue in Net+OS 7.1.10, or more general in more versions.

For its ‘normal’ use, my device accepts SSL connections on two different ports.
Besides that, CLI support is included in the project as well: standard plaintext telnet only, serial port CLI is disabled.

The problem: I can get into the CLI only when there is no SSL connection active.

Connecting to the telnet port while SSL is active works, but the logon prompt is sent only after all active SSL connections are closed (a fraction of a second after the last of those connections closes).

I’m reasonably sure that it worked in an earlier stage of development, when the other ports were still plaintext instead of SSL - but that was also under Net+OS 7.0 instead of 7.1.