Please post the screenshot of the Health Indicators tab from DriveDX or post the complete report here. The actual Health Indicators (aka SMART Attributes) contain the most useful information. Unfortunately Apple's SSDs contain very little useful SMART information.
See if you can run the SSD's internal selftests from DriveDX. If you are unable, then you can use the Terminal app to manually run the extended or long selftest. Open the Terminal app and type "sudo " without the quotes and include a space after it.
Right click on the DriveDX app in the finder and select "Show Contents", then navigate to "Contents --> Resources ). If this isn't correct you can keep searching until you find the "smartctl" program. Then drag & drop the "smartctl" file from the Finder. Then add the following to the end of the line to to initiate the extended or long selftest:
-t long /dev/disk0
Your command will look something like this:
sudo /Applications/DriveDX.app/Contents/Resources/smartctl -t long /dev/disk0
I'm assuming the drive identifier for the SSD is "disk0" which is shown in the DriveDX screenshot. Substitute the correct identifier if it is different next time you boot. The command will provide an estimate on how long it will take to complete and assumes the drive is not being used or it will take longer. Enter the following command:
sudo smartctl -l selftest /dev/disk0
After providing the SMART Attributes or the complete DriveDX report and you've run the SSD's internal selftests, I would suggest performing an ATA Secure Erase on the SSD which will reset it to factory defaults and can sometimes fix weird behavior. An ATA Secure Erase is a hardware feature built into many SSDs, but not all Apple SSDs include it (most do though) and can only be initiated using Linux tools. This is a last resort short of replacing the SSD.
You can try using the old free copy of Parted Magic (customized Linux boot disk) which includes a script making it easy for non-Linux users to Secure Erase their drives. You can get the old free version of Parted Magic from the MajorGeeks' link here or you can pay for the new version. Create a bootable Parted Magic USB drive using Etcher (Mac/Windows/Linux). Option Boot the Parted Magic USB drive and select the orange icon labeled "EFI". Once at the Parted Magic desktop there should be an icon for erasing drives. In the app, make sure to only select the "ATA Secure Erase" option which will require you to put the laptop to sleep & wake it up so the SSD is not "frozen". The app will then ask you for a temporary password necessary to activate the hardware security mode on the SSD which is necessary to initiate the Secure Erase command. Remember this password because you will need it to disable the drive's security mode if the procedure fails. Keep the password simple as it should only be temporary (maybe make it abc ). It can take anywhere from 30 seconds to 5 minutes for the process to complete although some drives can take longer. I usually just use a Knoppix Linux boot disk and manually enter the necessary commands to Secure Erase a drive. If the SSD disappears during this process then the SSD will be locked with the ATA Security Mode being set and the SSD will be unusable until it is disabled. Reply back in this thread and I can provide you instructions to disable the Security Mode.
After the successful Secure Erase, check the SMART Attributes with DriveDX to compare them from before and run the SSD's internal selftest again to see if they all pass.
It really sounds like the SSD has an issue. I recall Apple had a free repair program for SSDs for some systems around 2012-2013, but I don't recall the details on which MBAirs were affected. If none of the above help, then you may need to replace the SSD.
