HTML5: Dynamic plugins not loaded ("Cannot read properties of undefined")

Dear Community,

I am currently getting familiar with the HTML5/Angular based portal and struggling to get the dynamic plugins loaded. All dynamic libraries fail to load and I don't understand where to find the issue. I am quite new to this and struggle a bit.

Let me give a brief overview of the situation.

Used version:

OneIdentity Manager 9.1.1 with matching web project version

The problem:

The portal itself works fine in my local DEV envionrment with local API server, but all dynamic plugins fail to load. In the MS Edge Developer tools, I get errors like shown below. The example shows the error for the att module, but it applies to all of them. Only QBM and QER are fine since they are static.

ERROR [main.js:11116] Loading of AttConfigModule (att) failed with the following error: Cannot read properties of undefined (reading 'AttConfigModule') 
Caller: PluginLoaderService

What I checked so far:

I have a running imxclient.exe from the client software, the \imxweb subfolder contains the many Html_xxx.zip files for each module, and also the Html_xxx folder with the imx-plugin-config.json configured as described. I haven't touched anything there: It already came with the installation.

Sticking to the example, the att JSON file contains following data:

{
"qer-app-portal": [
{
"Container": "att",
"Name": "AttConfigModule"
}
],
"arc-app-certaccess": [
{
"Container": "att",
"Name": "AttConfigModule"
}
],
"qer-app-pwdportal": [
{
"Container": "att",
"Name": "NewUserModule"
}
]
}

The files were already available for the API server in the database.

I don't understand why the plugin wouldn't load, tried to stick to the documentation, but I must have overseen something. Anyone having an idea what I could check to make it work? Any help is much appreviated!

Kind Regards

Nikolai