Not sure then. Maybe try a different device with the latest version installed.
All the general troubleshooting for this is is 1) are you signed in 2) is the map enabled 3) do you have access to the content. As the owner of maps, with the same arcgis account in ArcGIS Online and in the Field Maps app, you should be seeing the maps you own.
From a user side I can only really suspect there is some confusion with the accounts e.g. maybe you are signed in with SSO into Portal for ArcGIS on Field Maps with the same username you have in ArcGIS Online. So you are actually connecting to two different portals with the same user account. Or it's device/software issue, so testing on another device could identify that.
If you can share some screengrabs it may help otherwise I'd suggest reaching out to technical support.
Here's an article showing more steps on the reasons we have already reviewed:
https://support.esri.com/en/technical-article/000025756