iMovie issues - iPhoto content not properly loading/displaying in iMovie on Mac

So I'm having issues I've never experienced before within iMovie. To begin, I'm just making family videos and all my content is captured through my iPhone and available to me on my Mac Desktop - all software is current as of this post. I updated settings from optimize storage to Download Originals because I lost a whole project due to the "Missing Content" black screen of death on most of my slides. This still happens to a few photos within my current iMovie project but only a few times to a few photos and its easily corrected. However, I continue to run into more issues new to me. Within iMovie my iPhoto content is all available and when I select an image or video I can see the content in full resolution and at original scale in the preview window to the right of the thumbnails, but I as soon as I add it into the iMovie project, it's cropped and the image quality is greatly reduced in that same preview window. This is not an issue with the auto cropping, Ken Burns effect, or anything else - iMovie is loading the content cropped and at a reduced quality. Content appears downloaded on the Mac when I view it in the Photos application. I was halfway through my current project when this began to happen and it has been unresolvable - and I understand all my editing options as I'm not new to iMovie. It seems most of the photo's are in the "RAW" format but not all of them. I've also had issues where I drag video into my project and the video shows in the project timeline but doesn't actually load/play. Again - all content is coming from iPhoto and was captured on my iPhone. Most of the video's I deleted and re-added - many times - before finally working. Last issue is my music - for some reason the songs I buy on Apple specifically for these videos isn't all auto loading from iMusic - I have to manually import now but never in the past; some songs that were there in the past are gone while others remain. I'm at a loss.