When trying to make changes to the Agent push page, it will say that the changes are saved successfully but leaving the page and coming back reveals that the page has returned to it's original settings. This can affect trying to change the target or schedule of the push policy or trying to change the list of computers in the manual push list.
ITMS 8.x
This issue seems to occur in environments where there is a lot of push activity occurring. If the push is scheduled to run too frequently for how many machines are targeted, it will not allow changes to be made to the Agent Push Page settings.
*Before re-enabling the policy you will also want to lower the frequency that the policy is running to avoid returning to this locked out situation. For more than a few hundred systems in the targeted list, set it out to at least two hours, if over a thousand systems then look to three to four hours.*