The Matomo module for Nextcloud no longer works correctly, mobile tracking no longer returns any information on the beta
Can you please make sure and test that this is an issue in Matomo and not the Matomo for Nextcloud plugin?
If it isn't please report it there: https://github.com/sualko/cloud_piwik
If it is, please provide more details as to how the tracking requests are failing (e.g. https://developer.matomo.org/api-reference/tracking-api#debugging-the-tracker)