I believe all the information I can give you are included in the screenshot.
The rest of the options is fine.
Old content displays a message telling to download an addon, and dungeons are working as intended.
nebularg commented
Do you have the rest of the BigWigs addons enabled? Do you have any errors?
PierrickF commented
Legion content was indeed not enabled in the addon list.
Oh boy do I feel stupid.
Thank you, and sorry.