Issue with Managed Properties based on Site Columns consuming Term Sets in O365?

So I have a term set configured at the Tenancy level (Admin) with some values (Categories). I need to use those values as options in various Site Collections in the Tenancy.

So in Site Collection 1, i created a Site Column (Col1), pointed it at the Term Set, all good. Same thing in Site Collection 2, another Site Column (Col2), assign to a list in Site Collection 1 and a Library in Site Collection 2 and items were merrily categorised and all was well.

Now i'm coming to show all this data in Search, so I create a Result Source that grabs the content from the locations the fields are used (one list, one library) and so far so good.

I then go go the Search Schema settings to map the Crawled Properties of Col1 and Col2 to a single Managed Property (knowing the values will work well together since they all came from the same source).

I want this so that I can use this Managed Property to filter the values I get back from the Result Source at the Search Results Web Part Level by a Query String (ManagedProperty={QueryString.Category}).

So to the issue; the second crawled property does not seem to pass any values back to the Managed Property, the only values I see are from Col1 essentially.

Further testing showed that mapping the Crawled Property associated to Col2 to any (new or existing) Managed Property would not result in any values being passed back.

I'm planning to rework the architecture to bypass the issue, but i'm intrigued if anyone can replicate this. It's as if once you hook up one Col to the Term Set, it precludes another from collecting values in the crawled/managed properties.