I'm getting the "Downloaded Content: You've reached the maximum number of downloads..." error message on the iOS Spotify app on my iPhone 6s, even when I'm downloading local files to my device from my computer.

Steps:

1. Before starting, I went into the "Offline Devices" section of my Account information and did "Remove All Devices", to make sure I wasn't using my quota on other devices.
2. I made sure that the number of cloud-based songs is under the documented limit. I deliberately created one playlist of all of my cloud-based songs, which has around 2900 songs, and created a second playlist of all of my local file-based songs, which contains around 2300 songs. First I successfully downloaded the entire cloud-based song playlist. Then I downloaded the local file-based playlist of all of my local files. It gets nearly to the end but now reports the aforementioned error and appears to show 11 songs remaining to be downloaded.
3. There is plenty of free storage available on my device (nearly 70 GB available even after all of the above downloads).

Note that the aforementioned documentation explicitly states, "If you're syncing your local files then there’s no limit."

Unfortunately, once it gets into its current state, it will no longer let me download any new cloud-based songs, even though I'm more than 400 songs below the 3333-song limit. 

Possibly related, but when Spotify is downloading the local songs, I notice that the progress count jumps around frequently, e.g. it might show "Downloading 300 of 2300", then "Downloading 600 of 2300", and then back.

Any suggestions for how to fix or troubleshoot this problem? Thanks.