Downloading from HiDive only produces *.M4S files

[petenun]

This just started happening in the last couple weeks, but when downloading any files (including those I've previously downloaded) from HiDive, the only output files are named "temp-######.video.enc.m4s.", with each file being roughly the size of a completed mp4 or mkv file. Multi-Downloader is running on Windows, and accessed from a different workstation via browser. I'm running version 5.1.5, with ffmpeg at 7.1, and mkvtoolnix at 89.0.

Any ideas on how to get Downloader to download full video files? I'm hoping this is just a newbie issue that everyone already has figured out.

latest.log shows the following:
Saving stream to «d:\temp\temp-655791.video.enc.m4s»...
Download and save init part...
Init part downloaded.
20 of 243 parts downloaded [8%] (4s | 1.1e+2Mb/s)
40 of 243 parts downloaded [16%] (4s | 1.1e+2Mb/s)
60 of 243 parts downloaded [25%] (3s | 1.2e+2Mb/s)
80 of 243 parts downloaded [33%] (3s | 1.2e+2Mb/s)
100 of 243 parts downloaded [41%] (2s | 1.2e+2Mb/s)
120 of 243 parts downloaded [49%] (2s | 1.2e+2Mb/s)
140 of 243 parts downloaded [58%] (2s | 1.2e+2Mb/s)
160 of 243 parts downloaded [66%] (1s | 1.2e+2Mb/s)
180 of 243 parts downloaded [74%] (1s | 1.2e+2Mb/s)
200 of 243 parts downloaded [82%] (1s | 1.2e+2Mb/s)
220 of 243 parts downloaded [91%] (0s | 1.1e+2Mb/s)
240 of 243 parts downloaded [99%] (0s | 1.0e+2Mb/s)
243 of 243 parts downloaded [100%] (0s | 97Mb/s)
Decryption Needed, attempting to decrypt
[ERROR] Failed to get encryption keys
[ERROR] Failed to download media list

client_id.bin and private_key.pem are functional in other programs and located in the widevine folder