What are those shiny things?
Normally those appear around place with collectibles but for some reason here there is nothing. Found multiple in High Isle.
Any idea what they are?
Pick it up and find out.
This highlight is typically used for collectibles that are part of a zone's "Museum Quest".
They originally started with the Orsinium DLC, where you're supposed to bring back artifacts of Orcish history to the House of the Glory of the Orsimer (which is essentially a museum, therefore coining said term).
In short, that's a task where you're supposed to find items hidden throughout the world (for Hew's Bane/Thieves Guild DLC) or in the local zone (most other content) and bring them to a central place related to the associated DLC or chapter.
Edit: I might have misinterpreted your question. If you see this, there should be something to interact with. If it isn't there, it's possible your client might think it's actually below the ground or some other obstacle. Try relogging and this might fix it.