TYPO3 Core

I encountered multiple issues with updated flexform data having no effect in FE.

While developing a plugin with a flexform, changes made to the flexform data weren't reflected in the FE output. After debugging the application and checking the saved flexform data in tt_content, it had to be some kind of caching problem. I tried "Flush frontend caches": no effect. I tried "Clear all caches": no effect. I then tried "Flush TYPO3 and PHP Cache" in Admin Tools/Maintenance: finally, the changed data was showing in the FE.

I noticed the same flexform had no problems with updating values on a different page, where the same plugin was in use. But that page was within the default site. The page with the flexform caching problems had its own site config, nested within the main/default site. When I removed the site config for the nested site (so that the page was part of the main site config), all updating problems were gone. A simple reload of the page in the FE was enough, no cache clearing required at all.

1. There seems to be some caching problem with flexform data and nested site configs
2. "Flush TYPO3 and PHP Cache" in Admin Tools/Maintenance doesn't do the same thing as "Clear all caches" (even though it says so: "This utility is also present in TYPO3’s backend: Top Bar > Clear Cache > Flush all caches")

This is obviously a serious problem, since regular BE users might have the right to change flexform data, but can't access the cache clearing in Maintenance.