FetchXML aggregate query resulting in Flow error "Key property is null"

[Lexicron]

I am working in Flow, using the List records action under the CDS (current environment) connector. I used Jonas Rapp's FetchXML Builder (FXB) to build a GroupBy+Aggregation Fetch XML query, using SUM for certain fields and COUNTCOLUMN for other fields.

1. In FXB, the query works fine without the unique identifier field (ver_answersid) of my CDS entity.

2. In Flow, however, it's giving this error: "Key property 'ver_answersid' of type 'Microsoft.Dynamics.CRM.ver_answersid' is null. Key properties cannot have null values." So, I added an attribute line for it in the query, as shown in the screenshot and code block below:

<fetch version="1.0" output-format="xml-platform" mapping="logical" aggregate="true" >
  <entity name="ver_answers" >
    <attribute name="ver_answersid" alias="ver_answersid" aggregate="count" />
    <attribute name="ver_classtype" alias="ClassType" groupby="true" />
    <attribute name="ver_rawscore1" alias="Score1Sum" aggregate="sum" />
    <attribute name="ver_rawscore2" alias="Score2Sum" aggregate="sum" />
    <attribute name="ver_rawscore1" alias="Score1Count" aggregate="countcolumn" />
    <attribute name="ver_rawscore2" alias="Score2Count" aggregate="countcolumn" />
  </entity>
</fetch>

It doesn't work.

Below are the alternatives that I've tried and the results I got from each combination in FXB and in Flow:

Attribute name	Attribute alias	Aggregate function	In FXB	In Flow
"ver_answersid"	"ver_answersid"	countcolumn	Error: Unexpected	Error: Unexpected
"ver_answersid"	<> attribute name	countcolumn	Works	Error: Key property null
any other field in entity	"ver_answersid"	countcolumn	Error: Unexpected	Error: Unexpected
"ver_answersid"	"ver_answersid"	count	Error: Unexpected	Error: Unexpected
"ver_answersid"	<> attribute name	count	Works	Error: Key property null
any other field in entity	"ver_answersid"	count	Error: Unexpected	Error: Unexpected
"ver_answersid"	"ver_answersid"	avg	Error: Not supported	Error: Not supported
"ver_answersid"	<> attribute name	avg	Error: Not supported	Error: Not supported
any other field in entity	"ver_answersid"	avg	Error: Not supported	Error: Not supported
"ver_answersid"	"ver_answersid"	max	Error: Not supported	Error: Not supported
"ver_answersid"	<> attribute name	max	Error: Not supported	Error: Not supported
any other field in entity	"ver_answersid"	max	Error: Not supported	Error: Not supported
"ver_answersid"	"ver_answersid"	min	Error: Not supported	Error: Not supported
"ver_answersid"	<> attribute name	min	Error: Not supported	Error: Not supported
any other field in entity	"ver_answersid"	min	Error: Not supported	Error: Not supported
"ver_answersid"	"ver_answersid"	sum	Error: Not supported	Error: Not supported
"ver_answersid"	<> attribute name	sum	Error: Not supported	Error: Not supported
any other field in entity	"ver_answersid"	sum	Error: Not supported	Error: Not supported
"ver_answersid"	"ver_answersid"	nothing	Error: Fetch aggregate requires all attributes to be either a groupby or an aggregate	Error: Fetch aggregate requires all attributes to be either a groupby or an aggregate
"ver_answersid"	<> attribute name	nothing	Error: Fetch aggregate requires all attributes to be either a groupby or an aggregate	Error: Fetch aggregate requires all attributes to be either a groupby or an aggregate
any other field in entity	"ver_answersid"	nothing	Error: Fetch aggregate requires all attributes to be either a groupby or an aggregate	Error: Fetch aggregate requires all attributes to be either a groupby or an aggregate
nothing	nothing	nothing	Works	Error: Key property null

I'm not doing distinct="true" and I'm not doing groupby="true" for this field, because those are not what I want. The values in this field are unique for each record and will void my GroupBy(ClassType) purpose entirely.

As you can see, nothing works in Flow. I've found other solved posts like this one from @Helpful and a blog post from Ryan Maclean where they managed to find a solution, however neither solution works for my situation. I strongly believe this is a bug in Flow. My original query from FXB without the key property/unique identifier should just work, it's perfectly valid. Flow's original error about "Key property is null" is ridiculous and points to a bug. The unique identifier field is a UNIQUE IDENTIFIER field, it's automatically ALWAYS filled with a value for each record, HOW can it be null??

Would anyone else have other insight or solution to this issue please?

[Lexicron]

Have raised a MS support ticket about this issue.

[Lexicron · Accepted solution]

Conclusion: Aggregation currently not available in Flow's FetchXML.

Also, aggregation by count is also not available in Flow's other CDS connector https://powerusers.microsoft.com/t5/Building-Flows/How-to-use-Aggregation-transformation-in-Flow-Lis...