Incoming call notification bug?

I'm running the Eragon v6.7 rom - fantastic work by Skeleton.
I use the Elephone smart view cover and have 2 SIM's fitted.

I've become aware of what may be a small (but inconvenient) bug and wonder if anyone else has experienced this...
Phone is in standby and the screen is off.
Incoming call is received and phone rings. Display remains off - i.e. nothing visible in the round clock window.
I open the cover - display wakes up but still no call is displayed.
I unlock the screen using the fingerprint scanner.
When screen unlocked the incoming call is shown in the notification area at the top of the screen.

Should not the incoming call wake the phone and enable me to see which SIM and from whom the call is from?

Is there a setting somewhere I'm missing?
Does anyone running a stock ROM know if the issue/problem is there also?

By the way, if the screen is still active, i.e. the clock is visible in the smart view case window then the incoming call displays showing caller and which SIM.

Any comments appreciated.
Thanks

Mike

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