Firefox drop down menu not showing current setting

TL;DR A drop down menu is always showing the same selection (before opening the menu) for Firefox alone. Other browsers show the current saved setting, but Firefox does not.

I have a settings page where users can choose their timezones. The user opens the drop down menu and selects their time zone, then clicks the button "Apply"

When the user does this, the page is reloaded, and the (previously saved) timezone shows as the selection for the drop down menu.

So the steps to updating your timezone go like this

• Dropdown menu shows "UCT"
• Open the drop down menu and select "Eastern Time"
• Click Apply
• Page reloads and drop down shows "Eastern Time" for all browsers other than Firefox

Is this a Firefox bug? I've turned off accelerating graphics, but this didn't resolve the issue.