I just put my Simbrief ID in the third-party options and when I try to import my flight plan from Simbrief by clicking in request company flight plan in the FMS 1, nothing happens, it don't import the flight plan that I created in the Simbrief, I wonder if it's a bug or if I am doing something wrong because I was some months without flying this airplane.

I had the same issue. I flought another airplane and the next time I used the A350 it was working again. but why?

No idea but I am going try to do it to fix

 

I just joined this forum for this same issue.  I previously used the SimBrief import option in the FMS, and it worked fine, but it only seemed to work before engine start.  Recently, it has stopped working.  I've tried different states, and tried inputting the Flight Number, but no luck.   The most recent update didn't fix it for me either.  
Still a fun plane and I use pretty simple flight plans so not a big deal but hope it gets fixed.  

Seems to only work - company flight plan request - prior to start of engine. If I load in on a runway, then doesn’t work. 

13 hours ago, BoeingSpeedbird said:

Seems to only work - company flight plan request - prior to start of engine. If I load in on a runway, then doesn’t work. 

You need to request the flight plan in the SEC FLN and then swap to active FLN and use the INIT (THIS IS WHAT HAPPEN IN REAL LIVE)

I’ll give this a try.