To begin with @SIMONSEF ensure there are no new app updates for those apps in the Play Store.
If not then consider going into Settings - Apps - Find the app - Storage - Clear the apps cache and data.
Current Phone ~
Samsung Note 20 Ultra 5G SM-9820 _256Gb SnapDragon 865+
Samsung One Ui 2.5/ Android 10.
I have had the same problem. I can upload stories from my ipad no problem, It is definintely a Samsing S7 thing.
The uploaded story will be 'posting with spinning wheel' for a day until it times out. It will never post.
I have uninstalled, reinstalled, updated to latest software update, cleared cache, logged out and logged in. There is nothing left to try.
If a fix is found please post.