I don't know where to start because Adobe PE 2018 has so many glitches, but I'll start with this.
I started off with PE 9, and been using it for 10 years for my series I have been doing with my studio production team, but recently I bought a new powerful PC and PE 2018 since it was the latest one out as well as Windows 10 does not support PE 9, and the thing is PE 9 never had this many glitches or let's just say I got use to the software. Right now from my personal experience, it looks like PE 9 is better than PE 2018.
When I load up one of the (PE 9) files on PE 2018, it opens fine, but there is a problem when saving the file (even with some recent work on it). I checked on the Windows explorer to see if the date had changed under Date modified, but nothing has changed. What I found out is PE 2018 can save a (PE 2018) file from scratch (which is normal), but cannot save a file from a previous software instalment (PE 9).
Also in the files I have, the videos/clips that is already added in the timeline (from PE 9) now comes up as 'Media Offline' (on PE 2018) and they don't come up in the beginning when PE 2018 asks where these videos files are in the 'Where is the File...?'. (When file is already opened on PE 2018 and clicked on the 'Media Offline' clip,) I found the exact video file(s) to replace it, but it tells me a 'Add Media Failure' Error: 'The importer reported a generic error'. Then when I go back to my old PC (which is slow) with the same file (on PE 9), it opens up brilliantly with no errors or 'Media Offline'.
It looks like Adobe didn't even test this product before they decide to sell this last year (2017). We all know programs have glitches, but no one should release a software with glitches and say something like, "because programs have glitches, we should just forget about it." Something like this, you got to think about the customer's satisfaction and the software's future reputation. I like Adobe and what they do to make a video editing software that is easy to use, but this is unacceptable. I don't think Adobe was meant to do this to their customers especially for me who has been a customer for 10 years, but the simple things is making it hard to work on even though I got a powerful PC.
I'm not sure how to respond to your post, gp, because I'm not sure if you're talking about Premiere Elements or Photoshop Elements, since either could be abbreviated as PE.
But if you're trying to open a Premiere Elements 9 project file in Premiere Elements 2018, that's just not possible. There are several generations between those programs, and the program was given at least one major overhaul in the meantime.
Beyond that I'm just not sure what to tell you since your post isn't even clear which product you're talking about.
Apologizes. It's Adobe Premier Element 9 and Adobe Premier Element 2018.
Okay. What about the clips/videos that works on Premier Element 9, but doesn't work on Premier Element 2018.
For those who are confused, it is Adobe Premier Element 9 and 2018, not Photoshop Elements.
But you can always check the tags of the post for clarification.
As Steve has said, Premiere Elements 9 projects will not open and work properly in Premiere Elements 2018.
Those two versions of the product are just not compatible.
I understood that from Steve, but how come some videos cannot open in Adobe Premier Element 2018, but all can open in 9?
Any help please on why some videos/clips will not open in Adobe Premiere Element 2018, but all will open in Adobe Premiere Element 9?
With the files not compatible with Adobe Premiere Element 2018, Adobe should have put in something in the software that when a user open older files, the software should bring up a message about the older files not being compatible and give you the option to saved the file in a new file of the software version.
Mixcraft, Fruitloops, Microsoft products and etc can open up older files and can save it in a updated/new software file or in Microsoft you have an option to save it in the older version or in the updated/new software file.