So I got a reply from Samsung and here it is. Haven't had a chance to try it yet. Here it is.
Thank you for taking the time to contact us at Samsung Technical Support. We always appreciate hearing from our customers.
It must be very inconvenient as your Galaxy S7 Edge is displaying SD card mount notification in every 5-10 minutes. I will provide you the information how to resolve this issue.
The issue might be with the SD card. The SD card you are using (128GB) should work fine as S7 Edge supports an external memory card upto 200GB. Please perform the below troubleshooting steps and check the result.
1. Performing soft reset might resolve this issue. It will not erase any data from the phone and will refresh the internal circuit of it. Press the Power and Volume down button simultaneously for 7 seconds and check the result after the phone turns ON.
2. Turn the phone OFF, eject the SIM card *** SD card tray from the phone. Remove the SD card and clean the connecting end using a dry cloth and replace the SD card and reinsert the module and check if you are experiencing get resolved or not.
3. Use alternate SD cards with your phone and check the result. It will help us to conclude if the issue is with your phone or not.
4. Insert the SD card in alternate phones and check if the issue persists with those phones. This will help us to isolate if the issue is with the SD card or not.
5. Any third party application installed on the phone might be the reason behind this issue. To ensure that, boot the phone in Safe mode and check the result. Safe mode will not erase any data from the phone. It will just block all the third party apps to access the phone. When your phone exits Safe Mode, some of your customization options (i.e. themes, wallpapers, etc.) may be reset to default. Safe mode steps:
a) Power off the phone.
b) Press and hold the power button until the phone powers on.
c) When the Samsung logo starts to appear press and hold volume down until the logo disappears.
d) The phone should now be in Safe Mode and "Safe Mode" displays in the lower left corner of the screen.
[NOTE: To exit Safe Mode, restart the phone. When it reboots, it will no longer be in Safe Mode]. If the issue was not there in safe mode, we can state that the reason behind the issue is any third party application that you have installed on your phone. Please uninstall all those applications one by one from your phone and check the result.
I am positive that performing the above troubleshooting steps will resolve the issue. Please feel free to get back to us, if you have any further questions. We will be glad to assist you.
Thank you for choosing Samsung products.