Inconsistent Asynchronous Remote Event Receivers (SharePoint Online)

Hello, we are using Remote Event Receivers (Asynchronous) in our SharePoint add-in (provider hosted) for performing some post-processing on document library items. Everything works fine overall, but once in a while the events are just not triggered.

Also, this is being observed only on SharePoint Online, the behaviour is not observed On SharePoint On-Prem.

Has anybody experienced the same?