My guess is that the linked post is exactly what happened, you used the flag in the building before you published the flag, so the game sees the flag in the building as a "private asset"...

I think that if you just opened the building in the editor and remove the flag, and re-add it using the published flag, it would be solved.

I have not got the time to look further into it but all prop I used are from the game (except for the flag ofc).

Maybe this is the problem:

"The workshop building tries to include Murka's Gazon (a prop) but the prop is not found. It is not found because it is not a workshop asset. The person who published the building probably published the prop as well but by mistake used the original, private, prop in the building instead of the published one.

You may find the published prop on the workshop. Unfortunately, it cannot replace the private prop. For the game, these are two different props."

I don't think so...

I can place the building without problem, the planters show up, the flag doesn't...
My guess is that there is a name discrepancy that happened between using the flag and uploading it...

here is a link to an image of the asset report and asset browser of the LoadingScreenMod on my Steam profile

Oh I misunderstood. Is it because flag can be animated ?

@TioAuditore, yes I am subbed to the flag asset... I'll place it by hand, no problem...
I just wanted to let you know that the flag in the building doesn't point to the flag asset in the workshop... I'm pretty sure it's only a minor naming issue, but some people will unsub for this, without telling you, so you never know why they sub/unsub and think they don't like your asset...

Great happy to add more Belgium retails :-)

Do you have the krefel flag asset ? It's available on my profile. Otherwise you can subscribe to the other version without any prop in it !

Nice, good to see some local retail on the Workshop!
LoadingScreenMod throws a missing asset error even though I am subscribed to the flag:

Asset bug: Workshop asset uses private asset (Krefel Flag.Krefel Flag_Data)

It seems the flag on the workshop isn't recognized by the game as the asset used, as the missing asset isn't linked in LoadingScreenMod, maybe a naming discrepancy?