hi Neil McConvey ashley thanks for reaching out! I'm Jess, the designer on Channels
unfortunately its a restriction on Google Play's end - you can backfill your own historical data by downloading the .csv file from your Google Play console and uploading on Channels as a new data source. let us know how this goes and thanks for your patience as we roll out different integrations all with different requirements!
for future questions on channels, can I please direct you to this 🔒[private feed], the team and I look through this every day to respond to customers