@Hubert Dudek​ , I have also tried your suggested first step, sometime after posting the original question. Unfortunately, that doesn't work either, which confuses me, since I expected it to work. I did think to write it to delta to benefit from the improvements that come with it.

df = spark.read.option('multiline', 'true').json('dbfs:/mnt/data/delta/bronze/BBR_Actual_Totals.json')
df.write.format('delta').mode('overwrite').save('/mnt/data/delta/silver/dev/all_json_data')

However, I'm getting some strange errors. I have attached the stacktrace as a .txt file, because it's too large for the body of the message. I'll just post a short starting snippet below. 

---------------------------------------------------------------------------
Py4JJavaError                             Traceback (most recent call last)
<command-467748691415734> in <module>
----> 1 df.write.format('delta').mode('overwrite').save('/mnt/data/delta/silver/dev/all_json_data')
 
/databricks/spark/python/pyspark/sql/readwriter.py in save(self, path, format, mode, partitionBy, **options)
    738             self._jwrite.save()
    739         else:
--> 740             self._jwrite.save(path)
    741 
    742     @since(1.4)
 
/databricks/spark/python/lib/py4j-0.10.9.1-src.zip/py4j/java_gateway.py in __call__(self, *args)
   1302 
   1303         answer = self.gateway_client.send_command(command)
-> 1304         return_value = get_return_value(
   1305             answer, self.gateway_client, self.target_id, self.name)
   1306 
 
/databricks/spark/python/pyspark/sql/utils.py in deco(*a, **kw)
    115     def deco(*a, **kw):
    116         try:
--> 117             return f(*a, **kw)
    118         except py4j.protocol.Py4JJavaError as e:
    119             converted = convert_exception(e.java_exception)
 
/databricks/spark/python/lib/py4j-0.10.9.1-src.zip/py4j/protocol.py in get_return_value(answer, gateway_client, target_id, name)
    324             value = OUTPUT_CONVERTER[type](answer[2:], gateway_client)
    325             if answer[1] == REFERENCE_TYPE:
--> 326                 raise Py4JJavaError(
    327                     "An error occurred while calling {0}{1}{2}.\n".
    328                     format(target_id, ".", name), value)