Its not making te thumbs because you don't have the writes to write to that directory, and you don't have rights to make the directory. Change to 777 and try again.
Don't you think that giving read, write, and execute permissions to everyone including the owner, group, and world at the directory level is a serious security disadvantage?
I can't think of any situation in working with Plogger that you would use the 777 permission level effectively at either the directory or file level.
That lack of security makes it easy for anyone that has access to your upload directory through Plogger to upload and execute a program that could bring the server down.
Plogger configuration suggests that a 755 is appropriate at the Directory, and a 644 at the file level.
For testing purposes I run all of my stuff locally 777 and then bring the permissions to the appropriate level when publishing a site.
Without changing any of your permissions do the following, b/c it seems your doing this on a live site.
In the root directory see if any thumbs are being created. See if you can drag and drop something into the thumbs directory. Check the permissions of the thumbs folder. Additionally see if your full size images are loading as well. Next check your php.ini file and make sure you have an acceptable limits in terms of memory, process times etc
The above image is what error i'm getting. Really causing me issues now - Can someone offer advice or recommend an alternative gallery management site?
Is it possible that you're sending the ftp images into the wrong directory?
The correct path from the Plogger root should be plog-content/uploads (e.g. Plogger/plog-content/uploads).
The Plogger root also has a plog-admin subdirectory with a plog-content subdirectory and an images subdirectory (e.g. Plogger/plog-admin/plog-content/images).
Since you're in the plog-admin directory when you do the import, that might be confusing.
Have you made any code changes to the plogger _install script or the configuration initialization routines? If not, you might consider a clean re-install in a test directory using ploggers index.php to start it up. You should then be able to ftp a couple of photos to the test uploads directory (e.g. Plogger/plog-content/uploads) and verify the operations and the thumbnail creations and display through the administrative scripts.
Sounds like a good idea to re-install. Your current images are in the sub directories of plogger /plog-content/images/. You can ftp them to a safe area either locally or on the server, do the fresh install and then ftp them to the new plogger/plog-content/uploads for importation after you are comfortable with the new installation.