Welcome to the forum.
Though with different file types, I have encountered similar - file Duration is mis-read in PrPro. Obviously, something in that/those file(s) header is being missed by PrPro. I have yet to find out what. As per your case, it seems to be with random files from what should otherwise be a simple group of the same file types, with the same exact conversion settings.
In my case, I get handed a lot of different file formats, and just use a conversion program to get those to DV-AVI (in my case) for SD Projects. Often, I will have a situation, rather like yours, where I will have 5 files, whose specs. all match up (same camera and settings in your case), and the conversion will be batched, and all resultant files identical. From time to time, one of those converted files will exhibit the same characteristics, as you observe. VLC, or other players, will see the full Duration, as will G-Spot, or MediaInfo. However, PrPro is missing something in that one file, and the Duration is heavily truncated, just as has happened to you. Quite by accident, I found that my PremiereElements program had no such issues with the "bad" file. It would Import and see the correct Duration, where PrPro could not. I just Imported, dragged to the Timeline, and then Exported to the same exact file settings, DV-AVI. The resulting file was identical to the problem DV-AVI that I had Imported. G-Spot and MediaInfo say it exactly the same. Various file "comparisson" programs could find no differnces between the two files, yet PrPro now saw the Duration correctly. I only wish that I could tell what went wrong, regarding the Duration in the originally converted file, and then the one that I just Imported and Exported from PrE, but I have never found the difference. I have opened the files in hex-editors, and gone line by line, and cannot find anything different between the two - but something IS different.
While I have no fix for you, I can add slight comfort by saying, "I've seen very similar, and in similar cases - conversion." My "workaround" involves some extra steps (plus an extra Export), in another Adobe program (in my case), so is not ideal. However, now that I know to be on the lookout for the possibility, I just watch those Durations closely, knowing that I might need to work on one, or more, of those files, to get PrPro to see the proper Duration.
Good luck, and maybe someone can offer us both a totally fail-safe method.
PS - I have encountered this with my old-fav, and generally flawless DigitalMedia Converter 2.7, plus several other highly recommended conversion progams, so it does not seem specific to any one conversion program.
converting the clips...to AVI
Using what codec?
Unfortunately Due to the scaled down properties of Premiere Elements I can't use it for this particular project.
I doing a straight 30fps non drop frame output with an output size of 256 x 256 square pixels.
I don't know what codec.
In my case, I do not edit in PrE, but use it as just a "conversion" program, to fix this one problem, when it arises. All editing is in PrPro.
Can you give us the full specs. for the files, that fail? Maybe something will stick out in those specs.
I don't know what codec.
Because some work well, and others don't.
Solved my dilemma using Windows Movie maker. When I took the files into elements I had the same problem. When I took the files into Movie Maker I was able to open the files the proper length and saved them out using the exact settings of my AVIs. I'm still waiting on the codec info to come but the project is now done and gone.
Thanks for the assistance, and the ideas.
the project is now done and gone.
Good news, and glad that WMM worked as a conversion program.
Good luck, and thanks for reporting your success.