I just checked, the exclusions do work.
Exclusions do not depend on the profile number. They belong to a profile but whether its ID is 1, 200 or 1,345,672,034 is irrelevant to whether they apply. To make it clear, the profile settings and the filters (including directory exclusions) are columns of the #__ak_profiles table. When a profile is being loaded e.g. as part of a backup they are all loaded simultaneously, as a single database record. While profile settings are encrypted filters are not so there's an even lower barrier to loading them correctly.
You do not need to manually exclude the output directory. As you can see, it's automatically excluded (red icons). All its files and folders are excluded but not the directory itself. This is on purpose. It's so that restoring the backup on a blank site creates your output directory as an empty folder. If it's completely missing, like you did by marking the first exclusion icon, restoring on a blank site will not have an output directory created and further backups will fail miserably.
Attachments in our ticket system work just fine as long as they are under 10MB and their extensions are bmp, csv, doc, gif, ico, jpg, jpeg, odg, odp, ods, odt, pdf, png, ppt, txt, xcf, xls, zip, 7z, rar or json. Note that the extension must be lowercase. The information about the maximum allowed size and the allowed extensions is exactly below the attachment interface. My best guess is that you're on Windows and somehow ended up with an uppercase .PNG extension which is actually not-standard. The only reason it works on Windows is because Windows is case-insensitive.
Regarding your issue, I have some ideas. The top suspicion is always a backup archive being left behind in the root of the site. However, I'd much rather see a log file from your last backup so I can tell you which large files or large directories were included in it. Please ZIP and attach your last backup's log file for me to be able to do that.