Thanks for reply, so it means RTT in DX12 still failed(at least temporarily)
Considering all the pain and reliability problems LM had switching to DX12, in addition to the fact DX12 lacks native support for DirectWrite required by Fonts ( unless you mix-up DX11 + DX12, for an even higher VRAM usage ) and we used an open source library to do all Font rendering which won't be ported to DX12, we explained a while ago to have dropped any plans to try porting the RTT features to DX12.
We had some hopes moving to HTML5 instead but, it seemed very unstable and, even LM themselves, in 5.1 HF1 switched BACK from Html5 to Scaleform for their own menus system so, if not even LM trusts their HTML implementation to be reliable enough ( the infamous Simconnect menu locks up that were fixed by switching back to Scaleform ), it would have been too risky for us using it anyway.
That left us with the only possible choice, which has always been our "Plan B": using the regular multi-liveries system like FSX, which we are sure it works.
And is it still flexible for assigning different logos for different airports/airlines by using new method? e.g. I assign a catering vehicle logo in a airport for an airline, and this configuration will be stored for next time, as RTT performance before?
You can still assign an operator logo for handling, catering and jetways for each parking, simply by selecting one from the list. So, it's definitely easy but, you can only choose from the list of about 200 stock operators.
However, it's not as flexible as it is in P3D V4 that, thanks to RTT, you can create a new operator from scratch and pick-up your own PNG image for the logo.