It looks like Parallels isn't going to do anything about this.
I remembered someone posted that they were using TotalSpaces2 to be able to work with Sync'd mutilpe fullscreen desktops. I have now given it a try and to my surprise it works!!
The set up I have gone for is:
Installed TotalSPaces2 (initially in trial node) having followed instructions and followed switching off & on SIP (Instruction on website).
MAC OSX (High Sierra) In Mission Control - Group Windows By Application
- Displays have seperate Spaces
TotalSpaces2 - In Layout - SyncGrids - Checked
- Added the correct desktop before opening Parallels
- In Transitions - Use Transitions
- Swipe to change Spaces (4 Fingers)
Then Voila - everything works as before.
I top this off with Hyperdock and it's nearly perfection.
I am not sure if you need all the above setting but it works for me.
Hope this help someone - I certainly feel it's restored me to 99% back to old PD11 - If only Parallels would do the same.
Ken
[I do not work for or have any connection to either Hyperdock or TotalSpaces2]
OK I gave up with PD11 too many issues with stability on OS X High Sierra and went for PD13, even though I got a refund on PD12 and I can see its still a problem, but went down the TotalSpaces2 route as suggested by Ken. Its taken a a good few hours and lots of crashing and re-booting but somehow its now working exactly as it should. I have tried all the configurations mixing options in Parallels Control Panel and the TotalSpace2 options, some options deliver 'Parallels' screens and others deliver multiple 'Windows 10' screens. I have managed to get it working under 2 or 3 options but the best seems to be...
OS X - Displays have separate spaces
Parallels Configuration -
Use all displays in full screen (checked on but is optional as can be selected from drop down menu when Windows is open)
Activating virtual machine shows all spaces, checked on creates correct 'Parallels' screens (which I think you want), unchecked creates 'Windows' screens, which generates extra blank screens (6 for me with dual monitors) and creates lots of issues getting rid of the ones you don't need.
My experience is...
**** checked on can cause a lot of crashes ***** unchecked requires moving (click on and drag) the second screen desktop using the OS X Desktop displays from one screen to the other (make sure you move the correct screen) for me its the 2nd desktop to the left of the main Windows desktop. It can be a combination of using OS X features to move the screen and TS2 features to set them up.
It takes a while to play with the TS2 options I have found it best to create 15 screens 1-15 for my apps and let Parallels add a 16th on its own, you will probably spend time adding and deleting screens in TS2 to see what happens. The resolution settings in Windows do NOT seem stable I have found I need to adjust the Display Settings to get the correct resolution on both monitors, once set its stable for that session. However, I do seem to be configuring bits each time after a log in and out or a reboot of the Mac. It is working and feels like I am getting a more stable set up each time I use it, which is not logical !!!
I would suggest adding a program name to each screen in TS2 it makes it a lot easier to use. Once completed it all works perfectly the same as spaces worked in previous OS X versions.
Only downsides are tool bar across 2nd monitor which greys out when not used and some issue with the cursor changing from black to white and size maybe on each monitor, which is a small price to pay.
Its not been easy and what has worked for me may not work for you, but this may be a useful reference for some. I am currently using a new top of the range 2018 Touch Bar Mac Book Pro
Thanks Ken for the info and encouragement to go and try it, Charles