Best in slot only shows me minimum changes such as changing conduits and Enchants, I know I definitely don’t have anywhere near all Best in Slot items, but it just shows me the same items I’m wearing.
This issue is only happening on one of my characters, not all of them
Based on that Snapshot, my conclusion is that you’ve favoured highest iL over highest throughput.
Example:
Best in Bags show your iL226 “Veinripper” to better than the il239 “Glaive”… along with a switch-out from Pelagos to Forgelite Prime Mikanikos.
There may well be situations where the highest iL may not necessarily be the best gear to equip; in this case targeting an iL239 or 252 “Veinripper” would be the way to go/end up.
Best in Slot is a disconnected appraisal of what the best all-round set of gear is; it doesn’t look at what you already have.
You may want to look into the Upgrade Finder/Add to Bags option to look for what gear to target; I added the Heroic & Mythic iL “Veinripper” to the Trinket you were targeting & got this:
EDIT:
I just noticed you have a Vengeance OS; that may affect your Havoc BiS setup, too.
I’m not a good enough player to be looking at Mythic Raiding gear, let alone a dual spec. character, so I may have that part wrong.