Hi
DcendentsThank you for your asking. Kindly provide the information below so that we could better assist you.
1. Your current firmware version
Setting >System>About Phone>Software information
If you try to update to the latest version, does the issue still remain?
2. Please check on your "Auto-start manager/Battery-saving options/Battery modes" settings
Mobile Manager>PowerMaster>Auto-start manager/Battery-saving options/Battery modes
If you have any further queries, please do not hesitate to contact me.