Final Cut Pro dissolves operation not allowed
Adding dissolves in Final Cut Pro can sometimes be a tricky situation. If you are getting the dreaded '1 frame dissolve' that you cannot adjust, here are two solutions to your problem.
Issue 1: Make sure you have enough handles for the length of the dissolve. For example, if you have a 30 frame dissolve that is centered on a transition point, you will need 15 frames of handles at tail and head of your adjacent clips.
To verify that you have enough handles, double click on each clip and check the available handles. When you double click on a clip within the timeline window, Final Cut Pro will load that particular clip into the Viewer window. Within the Viewer window, you should now be able to immediately see if you have any handles left, on the right or left side of the clip.
Make sure that your in-out points are not at the extreme edges of the clip. If they are, you will not have enough room to perform a transition. You can fix this by dragging your in point or out point (within the Viewer Window) so you have enough room for your transition.
*If you hold down the shift key while dragging an in-out point, both points will drag together without shortening or lengthening your clip.
Issue 2: There is one other strange issue, where even if there is enough handles on one side of a clip, Final Cut Pro may place a '1 frame' dissolve in place of your default transition. The dissolve will not start or end at the cut, even though there is enough media on one end.
Solution: Zoom into the timeline and delete the dissolve. Then re-apply the dissolve to the right or left of the transition area. When you drop in your transition, it should look like this.
DO NOT drop the dissolve off in the location as shown below. This will result in a one frame transition.
