While I looked through error messages in the SharePoint ULS logs I found the following weird, typos and other unnecessary rubbish messages:
ECB XML document WopiApplication_ECB_XmlDocument|external-https|5725923||1033|False|False|True is not found in cache. Create a new one. This should be called only if WOPI discovery related stuffs have changed.
security token ‘0).w|s-1-5-21-1343024091-179605362-1801674531-94444238caaed2-f121-4de2-bde0-cfa3ffb63dca_Intranet’ is found in the local cache, but it is expired. Returing Null..
Have you found any typos or silly messages in the ULS logs then please let me know.