I had the same issues with the version 2019 R3. Before I used the ANSYS Academic Edition without problems, so I was sure that the issue was caused by the ANSYS "fully" installation. After using google for more than one day, I didn´t find any solution helping me. So I started to uninstall and install again and again with every possible combination of CAD-Interfaces integrated. This didn´t solve the issue too. My next step was to investigate the data in the installation path. I picked subfolder "aisol" at first and compared the included files. There was a discrepancy between the ANSYS Academic installation and the "fully" 2019 R3. So I get deeper in it and tried to replace the whole folder in the "fully" installation path. This solved my problem, but so far I didn´t want to replace so many files as I guessed this would lead to several other problems using ANSYS. At the end I could figure out two files which are maybe missing while the installation process, "tbb.dll" and "DockingPane.ocx". So here are my steps in short:
0. Be sure to have back up of all, there is no guaranty this will work :-), I am not an official ANSYS employee, so it´s on your own risk. But you don´t need to use external or additional data, that has not been published by ANSYS Corp., additionally you don´t have to replace an existing file, you will just add some more by this procedure, so risk is hopefully low.
1. Use your installation medium and browse to the folder "corewb"
2. Inside this folder open/extract the winx64 zipped file
3. browse to the folder "../aisol/bin/winx64/"
4. there are "tbb.dll" and "DockingPane.ocx"
5. Select and extract to your installation path, e.g. "CProgram Files/ANSYS Inc/v195/aisol/bin/winx64/"
6. Be sure not to replace, just add! Else you should make a back up of the original files within the installation path.
7. Maybe some more files are needed in your case too. F.e. I was surprised that "CommandBars.ocx" was not needed, despite it was one of just two ".ocx"-files and sounds like it could have been necassary. Take care just adding some files. Else other dependencies can be affected and lead to other problems.
If you don´t have the originally installation medium anymore, you can also use the Acadamic free download, the files are included there too. I hope this will help!