The wiki for Quicken states that:
You are supposed to be able to apply this individually to any spell or spell-like ability it applies to by right-clicking the spell and enabling it through the dropdown menu, but Bug: using this method will make Quicken to only apply intermittently to those spells (this is a known issue). To avoid this bug, set all spell icons to use the Default setting for Quicken and only use the Quicken feat icon to toggle it. This bug does not affect other metamagic feats.
Thats the first I have heard about such a bug and I dont remember noticing it myself - so I am curious if that is infact a thing.
You are supposed to be able to apply this individually to any spell or spell-like ability it applies to by right-clicking the spell and enabling it through the dropdown menu, but Bug: using this method will make Quicken to only apply intermittently to those spells (this is a known issue). To avoid this bug, set all spell icons to use the Default setting for Quicken and only use the Quicken feat icon to toggle it. This bug does not affect other metamagic feats.
Thats the first I have heard about such a bug and I dont remember noticing it myself - so I am curious if that is infact a thing.