When you have elements with no alt-text you get accessibility errors when running the checker. However, if you right click on the error and choose "fix" and walk through the items and mark them as decorative, instead of actually making them an artifact it simply changes the tag to "Artifact" which is not a valid tag and creates other errors. You then have to go in and properly designate the objects as Artifacts properly for the other errors to go away. VERY Frustrating. Come on Adobe Acrobat!
This is a repeatable condition and needs to be fixed immediately please!
Setting something as an artifact is a state and not a valid tag in the tags tree. Very frustrating that one tool designed to fix an issue actually creates other issues.
Nice catch! I notice that the tagged pdf "best practice guide" talks about Artifacts as a semantic category, which should be indicated somehow in compliant pdf/ua files, but gives only very sparse recommendations about how to actually do this.
Also this guide states that the content of artifacts should be accessible (in contrast to WAI-ARIA's role=presentation), but again the exact mechanisms for doing so are not given. For example if an artifact contained a link explicitly tagged as a <Link>, which is not an unthinkable possibility - this would fail according to Matterhorn Protocol Checkpoint 01-004, which disallows tagged content inside artifacts. (Links aren't even formally specified children for tables of content!) So there are evidently some holes in the spec here.
When you say "You then have to go in and properly designate the objects as Artifacts properly", how are you doing that?