Sorted. For some reason I had two copies of each file. One in mpg which I couldn't import and one in TOD, which I have never heard of before but elements must have because it did import these files. All good!!
The .TOD files were introduced by JVC for their early HD files. They were somewhat similar to the JVC .MOD files, from their SD cameras. Both could cause a few issues in Premiere. Some other camera mfgrs. used those formats too, and some with variations, that made them even MORE difficult to edit.
Glad that you sorted it all out, and good luck,
Your mention of two copies of each file caught my curiosity.
Is the .mpg of the two that same exact footage as the one with the .tod file extension?
What are the properties of each?
Is the MediaInfo properties readout the same for both?
Congratulations on moving forward with your project. Good work.