I have a Habit ebike with 1,700 kms on it. I was having slippage on gears and my bike dealer fitted a new chain and new cable but now it is worse.
When looking at the derailleur in the 2nd gear from top (12 gears) I noticed that the chain engages only about 90 degrees whereas on my Marin with similar gears the chain covers about 160 degrees. I have much more mileage on the Marin and a lot more climbing without ever changing chain or cassette. The cassette on Cannondale does not seem to be worn. Would the small contact with cassette be causing slippage?