Understanding Office 365 ProPlus Updates for IT Pros (CDN vs SCCM)

Hi Petrokl Its hard to speculate or troubleshoot via blog forum. A few thoughts\asks\questions.

While updating from a file share is technically supported, its strongly discouraged. We recommend updating from CDN using Servicing Profiles. 

To my recollection, with you use a custom path, you need to ensure your downloading the LATEST build\version using ODT because we require the V32.cab\v64.cab as means to inform the client which build to consume. The build number you are making available on the file share must be higher than what is installed on that client. 

Troubleshooting is best done using tool Microsoft 365 Apps Deployment Log Collector .

Use a tool like Notepad++ to search all files from log output folder for string 'unexpected' for clues and to review configuration.