Batch download randomly failing

This was an issue reported perhaps a year ago and was fixed. I've recently moved to the batch upload / download APIs and am now seeing the following. The reliability of sync nosedived in the app after the reset switch, and I can now see the logs riddled with these:

```
Error Domain=NSCocoaErrorDomain Code=4 "“620836A0-98B4-402F-9ACD-10A67AB1D308” couldn’t be moved to “tmp” because either the former doesn’t exist, or the folder containing the latter doesn’t exist." UserInfo={NSSourceFilePathErrorKey=/Users//Library/Developer/CoreSimulator/Devices/3EB61F50-E618-45B1-878C-A36F11EC9BA8/data/Containers/Data/Application/2EF3A736-65AE-446D-957A-C5AEDB5195E7/tmp/620836A0-98B4-402F-9ACD-10A67AB1D308, NSUserStringVariant=(
Move
), NSDestinationFilePath=/Users//Library/Developer/CoreSimulator/Devices/3EB61F50-E618-45B1-878C-A36F11EC9BA8/data/Containers/Data/Application/2EF3A736-65AE-446D-957A-C5AEDB5195E7/tmp/o_u_k_8a3b7f1395ab4a59821ef8948c6d834fstarred_p__i__d_.col.gz, NSFilePath=/Users//Library/Developer/CoreSimulator/Devices/3EB61F50-E618-45B1-878C-A36F11EC9BA8/data/Containers/Data/Application/2EF3A736-65AE-446D-957A-C5AEDB5195E7/tmp/620836A0-98B4-402F-9ACD-10A67AB1D308, NSUnderlyingError=0x600003010900 {Error Domain=NSPOSIXErrorDomain Code=2 "No such file or directory"}}
```

I'm using v3.9.1 of the library