Thats not the problemo.
Just tried a straight file name no go.
Time to have Rick take a peek.

It appears that the file does not save to the server so it must be some permission issue. Possibly on the server side.

I was thinking along those lines too so I tried different files with no spaces or underscores etc. - no luck.

Thanks for taking a peek Ruben. I turned off hot linking protection - I had it on and it was causing an issue somewhere - I forget the details but it wasn't with my forums. But it is off at the moment. I guess I will need support for this one - it has been malfunctioning for too long... I too think it is likely a server issue but what is causing this behavior is beyond my knowledge and ability to determine.

Here is one last item to check.
Since you already did this below there should be a file in the attachment folder.
When you test the attachment directory in the ubb control panel. It will write a file called "test.file"
Ubb had to write this file somewhere because thats how it knows the path and permission checked out ok.

See if you can find this file anywhere on your site.
Maybe you have a redirect/rewrite running in htaccess and it is not where you think it is.

On the subject of hot linking protection in cpanel at lunar.
I just noticed today that all added style image sets don't display anymore. so I had to turn it off to make the images appear.
Also I noticed that file ownership has changed in the group/ownership of the files.
So this may be a double whammy to your problem.

I knew about the test file, and as a test I deleted it and just reran the test which as usual states the folder exists and is writable. I went back into the directory and the file "test.file" reappeared. So I tries another post with a file attachment and it still does not work from there.

I don't think this is related but I cannot toggle my hot linking protection on. It stays in disabled mode no matter what I do. I guess the most baffling thing here is that UBB Threads/server writes the test file but doesn't write any other file.

I have had enough for now... this is wayyyy too much for me to deal with any more. I do appreciate your trying though!

If you want to go ahead and open up a support ticket on this then I can take a closer look.

On the subject of hotlinking though I did find the problem. Using cpanel to change the settings that it had written a duplicate rewrite rule in htaccess. But it did not include the referrer so it was working kinda weird that none of my background images were working. So I manually edited htaccess and removed the duplicate line.

We can chalk this one up to a non-bug which I think we all assumed from the beginning as this was likely either a server issue or human error. The latter is the truth in this case. My bad.

In the attachments storage directory box I had entered "../user_files" instead of the FULL PATH which is the correct entry. The test script worked with this but it caused errors when attaching files with posts.

Why did I do it this way? Good question. When I was hosted on Network Solutions the path to the directory did not work for some reason and I resorted to the "../" method and it worked there. Earlier this year I changed to a new hosting company I kept the setting and like I mentioned, it worked in the test... but not in posts. One other oddity about this is that I also set the avatar storage directory the same way yet it worked.

Moral of the story: Just because it works doesn't mean it is correct.

And thank you Rick for the support.