GSX always worked like this for years if you start a flight on a gate that is too small for your airplane, you can't do anything with GSX. You must exit the parking spot, go to another parking that you can use, so you can change your settings and, eventually, either override the wingpspan for those specific gates that are too small or enable the option in the settings to IGNORE the parking size.
Again, I agree is not ideal you can't do anything if you start a flight on a gate that is too small but, as I've said, this is how GSX always worked since 2012 when it originally came out, nothing has changed in a recent update. We might update it to present a menu with at least the "Reposition" option, so you can go elsewhere easily, and all the various Settings buttons, so you can also change settings. But again, we never had this before, it always was like this, see this post from 2012:
https://www.fsdreamteam.com/forum/index.php/topic,6412.msg55949.htmlIf the parking radius is too small for my plane. It then says that I cannot get any ground services
In FSX or P3D, we could do multiple nested menus, so we had a separate menu for the Settings and another one for the Airport so, even if you couldn't call the (separate) ground services menu on a too small parking, you could still change the settings or the airport.
But in MSFS, there's just one menu that includes ground services, airport, airplane and settings, that's why you can't do anything on a too small parking spot. You are only see this now, because there's a new popular extremely large airplane that just came out, which has the highest Wingspan of all airliners.
In any case, with today's update, we changed the default for the "Ignore Wingspan" option, to be Enabled by default. If you already had it Disabled from a previous version, just start a Flight on a Runway (or a gate big enough), so you can access the Settings menu.