In June 2019 (post patch JY 2603), several homins have issue with invisible Mektoubs (they can access inventory, but the mektoub/Gubani/zig is invisible).
To solved this temporarily, players have to make macro to ask their toub to follow and they show again, but you have to launch the macro again after relog (all the solutions are in uni FR and EN) I tried it and it works 🙂
Macro is category: Animals/ Action: follow me/Animals : select witch you need in the menu 🙂
More on Macros and Mektoub FAQ. To User Manual.
French images: