Hi MichaelC362, could you compress your thumbnail file and send it to me? I will forward the file to the dev team for analysis.
You could you find it under the installation path. To check the installation path, you could run the installation.exe.
If you use the portable version, you could open the folder, find the folder "User Data," then open the account folder which you have this issue, such as Default or Profile 1/2, then find the folder "Mx Thumbnail."
For example: C:\Users\lenovo\AppData\Local\Maxthon\Application\User Data\Profile 2\Mx Thumbnail