Some Instagram users get their pictures deleted by Instagram for violation of Community Guidelines, for reaching upload limits or for unclear reasons related to their anti-bot efforts that seem to mistakenly block users/app/phones.
This is not seem to be an iGrann malfunction according to the users that solved the problem. However, there are some that we have not been able to help.
To check if this happening to you, try to login to iGrann, on your phone, with a different Instagram account and see if you have the same issue. If you are able to upload pictures with another account on the same phone, then Instagram is deleting your pictures on your existing account/phone. Also, you should be able to upload photos with your account from another phone.
Some users have solved the issue in the following way: login to www.instagram.com from your phones browser and change something in your profile (Ex: your bio, but NOT the username or password) and then log out. Usually, this validates your account
Most users with this problem have reported the problem going away after a few days. It seems to be a temporary block.