Originally Posted by pside15
Have you tried a different ROM? I'm using WC's ICS ROM and have no exchange issues at all.
Probably not going to help as it seems to be an ICS issue. I'm currently running WC's rom and it also has the issue of settings not sticking with Exchange, WC has mentioned this as well. It won't stick for me on both the Vivid and Generic build. More searching in the forum showed that it also is a problem with Sensation's ICS build.
The problem is not that Exchange won't work, it is that the settings (update frequency, days of mail, email size, etc.) won't stick and falls back to the default 15min 5kb 3days setting after reboot, this renders push unusable.
Right now the only solutions are either to use another 3rd party app for push, or wait until it is fixed by google/HTC.