I have an ArcGIS Server 10.5 feature service registered with ArcGIS Online added to a webmap which i'm trying to take offline. The feature service has sync enabled and is available for download in Collector, however when i try to download the map, the download makes it to about 3/4 of the progress bar then pauses for a long time and eventually fails with an error that says illegal start of token.
I am able to remote into the ArcGIS Server machine and see that the runtime geodatbase is created successfully and placed in the output directory. This geodatabase can be downloaded manually by requesting the URL for the file directly. If I use the GP tool to convert the runtime geodatabaes to a file geodatabase i can see that the data I requested is in the file.
The error logs for ArcGIS Server show that the request completed successfully.
Does anyone know why Collector might be failing to fully complete the download?