New Can't Switch Default Sms App Correctly

[s0r00t]

Model : Redmi Note 4
Version : EU 7.1.12

I'm trying to use Signal Private Messenger (org.thoughtcrime.securesms) as my default SMS app. However :

• The default Messages app will take care of random incoming SMS
• If I disable the SMS permission of the Messages app, not only it will crash, but Signal won't receive incoming SMS at random, so many SMS are lost

However, I can send SMS perfectly with Signal. Receiving is the problem.
I :

• Installed Signal
• Chose it as default SMS app in the phone's options
• Changed its permission in the Security app (so it can start itself in the background, and another SMS permission IIRC)
• Tried disabling battery optimization for Signal; it did not change anything