@dollyb 
That's because when you've added another dependency on Databricks, it doesn't really know which one it should use. By default it's using built-in com.google.cloud.spark.bigquery.BigQueryRelationProvider.

What you can do is provide whole package name into format(), ex.

spark.read.format("com.google.cloud.spark.bigquery.v2.Spark35BigQueryTableProvider")