Folder modification time in MAFS (Microsoft Azure File System) is not updated ! Splunk is unable to properly monitor the folder as there's no change triggering ingestion of the new files. This is not a bug in Splunk, but limitation of the Azure File Storage ... even windows explorer and Azure web interface are showing creation time as the last modification date !
manually update your file modification time, to force detection.
The only workaround we were able to come up with (that actually works) was to update the destination folder last modification time manually
(e.g. by using a script after uploading log files):
(Get-Item ).LastWriteTime = Get-Date
restart splunk on a regular basis
reload splunk inputs on a regular basis (not to often if you have too many files to scan each time)
example : splunk internal call /data/inputs/monitor/reload -auth admin:changeme
Or not monitor Azure, and copy the files outside of the mount each time.