Continuing difficulties with audio when importing .MTS files

I'm using Premiere Elements 2019 to process video files from a Sony HXR-NX100 camcorder. This camera saves video as a series of 10-minute-long .MTS files, and my videos are 30 to 70 minutes long (therefore several .MTS files). The objective is to edit and post the videos to our YouTube channel in a 1080p format.

When I import the files into Premiere Elements, the program hangs part way through "conforming" the files -- it gets through maybe the first 10-minute segment or so, and then freezes in "conforming" at some percent of a later segment. This happens when I let Premiere Elements import the video from the SD card (it copies them to my hard drive), use Organizer to copy the files into an album on the hard drive, or manually copy the entire SD file structure to the hard drive and have PrE pull it from there.

This problem only started happening about a month ago, after a Premiere Elements patch (not an update to 2020). Before that, once I had learned to import from a file structure that reproduces the SD card's metadata and folder structure, it all worked OK.

After the problem started, my work-around has been to convert the .MTS segment files to .mp4 files with Handbrake and then import those. Once the segments are assembled in Premiere Elements, it is necessary at each join point to delete about 17 to 20 frames of silent audio, and a like number of black (or frozen-image) video frames but with the start of the video deletion offset about 15 frames past the start of the silent audio. I must usually unlink the audio and video tracks to make the necessary cuts, but this operation, combined with some delete-with-merge, gives appropriate continuity of the subject matter.

But we have more problems: A video file prepared in this way and then exported as an .mp4 file, seems to be corrupted in some way that causes YouTube uploads to stall at a particular percent uploaded (sey, 44%) and start the upload over again from the beginning. YouTube will do this any number of times with the file.

Running the Premiere Elements final .mp4 file through VLC gives a much smaller (and, I assume, lower-fidelity) .mp4 file which does upload to YouTube -- but this is a piss-poor solution. In fact, the need to render the .MTS files to .mp4 (Handbrake, requiring 2.5x the recording time to complete the job; doing all the cleanup at the join points; and re-rendering Premiere Elements' .mp4 file with VLC) turns editing a 1-hour video into an all-day ordeal.

Uninstalling Premiere Elements and reinstalling the original software download from a year ago also did not fix the problem.

(I was ready to punt Premiere Elements and give Corel VideoStudio Pro [$39.99] a try, but its install file rejected the furnished license key in a was that three separate Corel techs could not explain or fix after remoting in.)

Any advice on this? I could go ahead and spend the money for Premiere Elements 2020, but I am reluctant to throw close to $100 at an update of the same program in hopes that the problem will disappear. Jumping up to Premiere Pro and paying close to a thousand dollars for a year-long "real" support package is out of the question.

I am thoroughly frustrated with Adobe's product, and I don't see any good alternatives. Any effective help would be greatly appreciated.