Issue description:

Some customers, including us internally, regularly have problems displaying DWG previews in windows (10)  file explorer.
Sometimes there is no thumbnail at all


sometimes we only see the thumbnail in the right side panel but not on the file

  1. Check whether all files including the other file format except the DWG file can show the thumbnail or not, if others cannot either, please check the following ways.
    https://www.youtube.com/watch?v=laX-hxNiOIU

  2. If others can, check whether all DWG cannot, you can also create a new DWG, with the thumbnail save, you can set it in the options dialog box as below figure shown. Or you can test it in a OK PC, then try it. If it still cannot show the thumbnail, then just go to the solution below to check.
    How to preview DWG file in Windows Explorer Preview Pane?

  3. If only some of DWG files cannot show the thumbnail, maybe it is because the file doesn't save the thumbnail, so just open and save it again in ZWCAD with the thumbnail setting on

  4. As to the 2nd case shown above, I think user is showing the files in list, please switch to the content mode, then it should be ok.