Problem:
Some users may find that after upgrading to 2019 SP2, the Properties palettes displays in white background, like this:
Cause:
We have improved the experience of the properties palettes in 2019 SP2, the reason for this problem may be that the related file hasn't been replaced by the new file completely, so this error would happen.
Solution:
Please try to delete the en-us folder (For the English version) which is located in the following path:
C:\Users\[username]\AppData\Roaming\ZWSoft\ZWCAD\2019\en-US
Then restart ZWCAD, the problem should be solved by now.