7562 - Radiant: The synthesis design process does not complete when synthesis is run on Synplify Pro OEM
In Radiant, the synthesis and post-synthesis processes are a combined process under "Synthesize Design". When you run synthesis using the standalone version of Synplify Pro, this version generates a .vm file which will be used to run post-synthesis inside Radiant.
When the user runs in the standalone Synplify Pro, and then switches to Radiant, Radiant checks the time stamp of the //_.vm file. If the .vm file is newer than all RTL source files & pre-synthesis constraint files, Radiant resumes from 'postsyn'. If the .vm file doesn't exist or is older than any input RTL source and pre-synthesis constraint file, Radiant will resume from Synplify Pro. Please check the .vm file timestamp in your case.
For Example:
1) You ran the Synthesis on the Synplify Pro OEM by clicking RUN

2) This will generate a .vm file under the Design implementation folder.
Looking into the RTL which is older than the generated .vm file

3) When you try to Ran now on the GUI it will only run Post-Syn (To check this, the .vm file should not be overwritten and should have the same date)
As you can see, under synplify pro report, it still uses the older data taken from Synplify Pro OEM and .vm file is not overwritten.

Note: If you try to "Force Run" the synthesis process it will rerun the whole Synthesis process. If you only desire to run post syn with the existing results from Synplify Pro Oem, just select the "Run Synthesis" or Click the "Synthesize Design" button.