Let say I have custom app called abc, and module xyz inside it, and I have a self-hosted production frappe installation. but when I install it via frappe docker, I can see my app listed in about page, but not in list-apps, and when I execute background jobs, it is always saying Module Not found: xyz , and also when I install my custom apps, it always complaining that my app is not in apps.txt
Check if your module name exists in the Module Def DocType.
It exists in Module Def Doctype