For dual SIM phones, should display the signal strenght of the default calling SIM on the car display

[Yuri]

I have a dual SIM phone (bq Auaris 4.5) with 2 SIM's. My phone is paired with the hand free device of my car (device BMW 66304).
As I'm a frequent roaming user, I have 2 cards:
- one used for placing/receiving call, from country A. I use also the data network when I'm in country A, but data roaming is disabled. This card is set as the default SIM for issuing calls (SIM #2).
- one used in country B (SIM #1), used only for using the data network: this card is set as the default SIM for data network. Roaming is disabled.

When returning from country B to country A, both cards switch to an another provider: the first one to its normal provider (so, switching from the roaming status to the non roaming status), the second one switch to an roaming provider (so: no more usable for data network).

The phone hanset show 2 strengh indicators which are normals: let say 4 bars on the max. of 5 bars for both SIM cards.

The issue is that the car display show a triangle and no signal strength level (see attached picture). May be due to the fact that the SIM from country B was in roaming mode and not usable for data network due to its roaming status ?

The car display has to show something else:
- in my opinion, the signal level of the card defined as the default for receiving calls
- or at least one of the two signal levels of the cards