volgen :)

run
Compact & Repair
before you save accde file

Sami thanks for your reply, I have added that to my list. Unfortunately, it did not help in my case.

Your running it from the same computer? Is it in the exact same file location? It sounds like a Trusted Location problem. I'd check that first, I don't know your settings, but it could be something simple like a file name or the "include subfolders" check.

Do you have any other code running in like the on open/current of the main menu that could be getting it stuck? (Along those lines, you could try adding a Msgbox "Hi" to your main menus on open event, that would tell you if VBA is working)

Check if you have any empty procedures in your form modules (see picture below).  That could cause the resulting .accde file to have non-functioning buttons.  Compiling the module should automatically remove empty procedures, but sometimes it doesn't, as the picture below shows.  In that case, you need to decompile and re-compile the database.

Anyone can recreate this "bug":  Create a new .accdb, create a new form, add a button with an On Click event procedure that does something (open MsgBox, open another form, whatever).  Then add another event procedure (Form_Open, Detail_Click, anything will do, but has to be an actual form event), and leave it empty.  DON'T compile the code.  Save and close the form, then create an .accde file from the database.  Open the .accde file, open the form, and you'll see that clicking the button does nothing -- all because of the empty procedure, apparently.  As I said above, compiling the database should remove all empty procedures.  But I've seen that once in a blue moon it doesn't.

I will check that as I might have one, or could it be that I have a subroutine to two that I don't use?

Would there be a way to search for those empty routines? I have found 2 so far, but going through all the modules is tedious.

Compile the database and make another .accde, and see that fixes it.  Also, you only need to find empty procedures in the form module(s) of the form(s) that have problems in the accde.