SayIntentions.AI Integration not working

[CirrusPilot]

I prepared a SimBrief flight plan from EGLL to EGPF. After spawning the A350 at EGLL, I followed the steps of entering my credentials in the EFB. Then, from FLTOPSSTS, I imported the Simbrief flight plan into the A350. Then, I pressed INIT and imported the flight plan into the FMS F-PLN page. I then pressed ATC COM button. I selected the SAYINTENTIONS button and inserted EGTT into the NOTIFY TO ATC box and pressed the ENT button. A message appeared in GREEN which read NOTIFIED TO EGTT AT 1900Z. Nothing happened after that. When I check the SayIntentions ACARS network my flight did NOT appear. 

I then switched to using Bridge software and the FSM website ACARS client. Using the exact same credentials, I was able to connect to the SayIntentions ACARS server without difficulty, and using the FSM web ACARS client, I was obtain a a PDC and METARS promptly. So, I can connect through the third party software but I can't connect using the A350 software. I tried cennection to EGLL and the result was the same: able to connect through the Bridge/FSM software but unable to connect using the A350 ATC COM page. Has anyone else experienced this? Is there a fix?.