Is the input parameter permitted in config files?

Using aws-encryption-sdk-cli/1.0.2.3 aws-encryption-sdk/1.3.2 on Windows 10.0.14393.1770, PS 5.1.14393.1770

I have a config file, encrypt.conf, with the following contents:

--encrypt
--input .\TestCLI\Hello.txt
--output .\TestEnc
-S
@cmk.conf  #Includes a CMK ID, not ARN

When I run it, the command fails because it can't parse the input parameter in the file.

(py) PS C:\ps-test> aws-crypto `@encrypt.conf
Invalid source.  Must be a valid pathname pattern or stdin (-)

I created another config file, encrypt-no-i.conf, with the same content, except that I omitted the input parameter.

(py) PS C:\ps-test> cat .\encrypt-no-i.conf
--encrypt
--output .\TestEnc
-S
@cmk.conf

Then, I copied the --input parameter from the encrypt.conf file and added it, unchanged, to the command line. This command succeeds. (Overwrite is expected.)

(py) PS C:\ps-test> aws-crypto `@encrypt-no-i.conf --input .\TestCLI\Hello.txt
2017-11-15 08:43:16,765 - MainThread - aws_encryption_sdk_cli - WARNING - Overwriting existing target file because no action was specified otherwise: .TestEnc

I thought it might be a problem with the relative path in Windows, so I created a config file with the fully-qualified input path. I also tried a directory as the input arg + --recursive. That failed, too.