Problem with changing a quantity in Prestashop 1.7

Hello, I use multishop feature in Prestashop 1.7.7.8 It gives a wrong error message when changing product quantities in "All Shops" mode. It says "Unable to update settings" although in reality the product quantity gets updated. If I change the quantity of 2 product combinations, I have to click "Save" for 3 times to get the message "Settings updated". If I change the quantity of 1 product combination, I have to click "Save" for 2 times to get the message "Settings updated". There are some rare products where updating quantities is not possible at all - even in Shop1 or Shop2 mode. Second issue: in smartphone the homepage of Shop2 is redirecting to homepage of Shop1. This issue is not present in PC mode. If some Prestashop files are required to change, please provide the fix in a written way, so I can apply the fix for future Presta upgrades. Thank you!