Attachment section does not appear after upload

OK,
So, if it is an image, I guess you have somme issue with thumb generation.
Most likely, php user don't have write access to /projeqtor/files/thumbs folder (or no right to create that folder if non existing).
Or possibly some graphic library is missing.

In all cases, you must have some error loggued in projeqtor log file.

I looked again in log files you posted.
I finaly found on oldest one (I must admit I first looked only at the 3 most recent ones) :

2015-11-16 11:17:00.908 ***** ERROR ***** ERROR *****
2015-11-16 11:17:00.908 ***** ERROR ***** on file '/var/www/html/projeqtor/tool/saveAttachment.php' at line (244)
2015-11-16 11:17:00.908 ***** ERROR ***** cause = mkdir(): Permission denied

It is clear : php user don't have write rights on /projeqtor/files folder to create the expected thumbs folder.
So either give write rights to php user on /projeqtor/files
or create /projeqtor/files/thumbs and give write rights to it for php user.

Please see the following screenshots for permission for files.
I believe the permissions are okay?

Yes, they seem correct.

Is it normal that the thumbs folder is completely empty?

Not it is not, it should at least contains thumbs for attachements as a picture.
And the issue sure comes from this point.
New must understand why generation of thumb fails...

Are you sure you have nothing in ProjeQtOr log files ?
And maybe in Apache error log file ?

Could you also chack prerequisites as defined : www.projeqtor.org/en/product-en/technica...uct-prerequisites-en