Hi David Wong,
Thanks for posting in Microsoft Community.
According to your description, we understand you have issue that SharePoint list doesn’t save changes, it only saved changes for 2-3 minutes and the it reverted to the unchanged version.
For the situation you encountered, we do understand it has affected your work. Very sorry for the inconvenience caused.
We'd like to help you do troubleshooting for the issue. Appreciate your understanding that sometimes the initial reply may not resolve the problem very soon. However, we can work together to narrow down the situation. Please kindly provide more information to let us work further.
1.How do you edit items the SharePoint list? By clicking the item and then make changes?
If you edit the list in grid view, does same issue still happen?
2.Does the issue only appear when you edit the SharePoint list in a specific browser? If you try different browsers such as Chrome, Edge and Firefox, does same issue still happen?
3.Does issue only appear in the specific SharePoint list? What about if you edit in other lists in the same SharePoint site?
4.You mentioned "From the list modified by record, it show that it was from an user account." Do you check the record by checking the Version History of the items in the SharePoint list?
About the user account showing in the record, may I know whose account it is? Does the account belong to one of the 2 members in the SharePoint list?
Thanks for your patience and understanding!
Hope you have a nice day and stay safe and healthy always.
Sincerely,
Tina | Microsoft Community Moderator