Perhaps this documentation link will help. https://docs.sdl.com/806356/812665/sdl-tridion-docs-14-sp3/rendering-behavior-elements-in-------------behaviorconfig-xml 

Hi Pam, thank you for your response, but this documentation talks about "elements" and not "attributes" please refer to the screenshot I had attached to my initial post. Thanks

Understood. The attributes are usually read from the XSDs directly and they show in the side panel. Perhaps someone else would have insight into what to look at in your XSDs. 

Hi Pam, we are using the same XSD's we used with Create/Xopus and Reach/Collaborative Review. I wonder if the XSD requirements changed between the two products. If so, would you have any insight on how to migrate them?

Using the same XSDs is the best place to start. That said, different tools may interpret XSDs differently. I'm not an XSD expert. It seems like there's something that needs to be slightly changed in order for your attributes to be recognized. Not sure this would be helpful, but perhaps use the OOTB XSDs and validate that those attributes display and then review the syntax and compare to the syntax of your XSDs. 

Hi Pam, thank you for the suggestion, I look it and ran with it. The issue was with the sample behaviourConfig.xml in the documentation. The following config was setting all the attributes to "unconfigured element". Once I remove it, all attributes showed up as expected.

<behaviorscopegroup name="Common for all DTDs/schemas">
		<behaviorgroup>
			<blockgenericicon xpath="self::*" icon="sort-alpha-asc" 
       tooltipquery="./string(node-name(.))" priority="-5">
				<label>Unconfigured element</label>
			</blockgenericicon>			
		</behaviorgroup>
	</behaviorscopegroup>

Excellent and thank you for sharing the resolution with the community. 

Excellent and thank you for sharing the resolution with the community.