@Fallowo76
In addition to the local settings on the mobile, there are also general settings for each mobile number in the Customer Centre:
My swisscom > Your products > Mobile > Blocks & Roaming settings
Since the settings in the customer centre have priority for the operation of the SIM card, I would check whether roaming is generally enabled for your number or whether a "tick" has "crept in" when blocking roaming.
to check it's also possible to use the functions of the
Cockpit: Enter mobile number (swisscom.ch)