Unable to export or save video from iMovie

i am using a 128 GB iPad Air 2. I successfully last week created an iMovie, saved it to my iPad and uploaded it to YouTube with no problems. Today I made another iMovie that is 53 minutes long. I have 26 GB of free space (Had 36 before I started this). I tried saving the video in 4K and it told me I had insufficient space and that 21392.8 MB was needed to share the video. I tried saving it as a 1080p video and it started to export. When I checked in on it, it had failed and now says I only have 26GB left (so it ate up about 10GB of space but the video is no where to be seen on my iPad). I have no idea why I would need more space when I already have ample space on my iPad already. Any suggestions?