I think your problem is here:
Go to MSG.
Enable the following on UART1 with a rate of 5
But according to the protocol document on this command:
Send rate is relative to the event a message is registered on. For example, if the rate of a
navigation message is set to 2, the message is sent every second navigation solution. For
configuring NMEA messages, the section NMEA Messages Overview describes Class and
Identifier numbers used.
As you note, GAGSV for Galileo is not being sent, so SVINFO is your source for Galileo info. You are getting GxGSV messages each cycle, but SVINFO every fifth cycle. Isn't this what you are seeing?
You just need to change your SVINFO message rate to 1.
BTW, UBX-NAV-SAT is preferred, as UBX-NAV-SVINFO is only retained for backwards compatibility (see protocol spec). And you really don't need both GSV and NAV-SAT/SVINFO, I use only NAV-SAT, as it handles multi-GNSS much better.