Do I understand this correctly, you used the export options from the menu in an old game version to create a file of one of your save slots, but you can't import it into the new game version?
Perhaps the created file isn't fine. Have you tried to create it again? Or for other save files?
Has the import/export worked for you in previous versions?
I assume you use the itch app? Another way to install the game is to directly download the .apk. A direct install can be updated with a newer .apk when an update comes. Updating the game this way does allow you to continue your progress in the newer version without having to transfer save files.