If a new fixture is added when in "All Fixtures" view, it appears as a new tab. If the new tab is opened, switching to tab view deletes previously selected fixtures from both tab and "all fixtures" views.
After this, the general tab still displays the list of fixtures previously selected and those fixtures are not available for selection in the select fixtures list. Deleting the whole list leaves the tab for the new fixture while removing its entry in the list.
Deleting only the defective fixture descriptions in the general tab results in all fixtures being delected from the scene.
I am running QLC+ on Ubuntu 12.04
FUNCTIONS EDITOR BUG WHEN CREATING NEW SCENES IN QLC+ 4.3.3
Apologies. Copied title from my word processor file and forgot to change it - no ulterior motives!