Ok, I think I found the issue - it was only if you followed a certain order of steps, which made it tricky, but I did find it. See if you are experiencing what you're expecting now, and let me know if this occurs with any other popup form submission, because this bug could be elsewhere.
I went throught the "Search" menus (FA, player, coach) and all three worked for me when doing a filter search.
I tried other filters under the "My Team" menu and all seem to work except loading a game plan. Here is the steps that I
take if this helps.
1. mouse over "my team" menu
2. click on "gameplanning". gameplanning page comes up fine.
3. click on "load". Load Gameplan filter screen comes up.
4. I choose a gameplan to load from the drop down.
5. I click "load gameplan" button
6. the screen goes to loading with a "please wait". no problem there.
7. then the page loads but goes to the league home page, instead of loading the gameplan page.
I can then go back to the gameplanning page via the "my team" menu and the desired gameplan has loaded.
hope this helps
thank you for your efforts