Hi,
A few users of Exchange organisation have ActiveSync enabled on their mailboxes.
For some reason these few users have calendar sync enabled, but their calendar on their mobile phones have a 1 year history.
Other users can retrieve more than 1 year just fine. There is no company wide limit or restriction configured so everyone should be able to retrieve all.
I can reproduce the problem with a specific mailbox on multiple phones using different Android OS (7 and 8 tested) and iOS.
The user/mailbox that doesn't have this unexplainable restriction is fine on all phones and their OS.
The configuration is set to synchronise all, it just won't sync anything older than 1 year for a few mailboxes. I've tried finding a responsible parameter with exchange powershell, but so far I haven't found anything that seems related to this behaviour.