I experienced the same lately: when restarting maxthon no last sessions available all of a sudden. I then did a clean install and tested: last session appearing as normal. Then i copied the user-data folder in the new installation directory: all went fine. Then i opened all tabs i remembered from the history and BINGO: after closing maxthon and restarting it the last sessions were again gone.
Then in opened the tabs again one by one and closing and starting maxthon, there is where i found this site to be the culprit:
https://www.salusi.nl/tinnitus-behandeling-oorsuizen-genezen/
Every time i close maxthon with this site and starting maxthon again the last sessions where again gone.
How can this be?
BTW Happy new year everyone