I added a few custom applications from Office store into our O365/SharePoint Online 2013 and they were smoothly installed and became visible in our Site Content. Only problem is that if I try to click one of them to configure the options all I get is a messed up page with some kind of weird patches of icons/images and text all over the place. If needed, I can try to install the apps again and take a screenshot of the problem/situation later today.
I searched the internet and learned that somehow the app configuration page cannot load CSS styles so that's why the page is messed up. I wonder what is causing that? I have a global alternate CSS file loaded in the Site Collection root site but there aren't any radical changes.
Also I noticed that when I clicked the app to get into the configuration page, it modified the URL by adding an ID of some kind (numbers and letters) after my domain part like this
https://mydomain-xxxxxxxxxx.sharepoint.com and normally my URL would be just
I appreciate any help on this matter!