Ajax Error Get Listings

Current WP v5.2.1 with unique plugin CiviCRM (manual install). CiviCRM used by over 11K non profits today with enormous WP following which is why they designed the fork. With that said, the issue is an Ajax error somewhat cited below. I have only bought one add on so I’m ok losing the money; I am more interested in how to troubleshoot the plugin incompatibility as I have zero issues with the dozens of others I run. Created a ticket on the matter, but am hopeful to reach out to the community. Have also brought in CiviCRM.

JQMIGRATE: Migrate is installed, version 1.4.1
jquery.js:4 POST https://www.iafst.org/jm-ajax/get_listings/ 500
send @ jquery.js:4
ajax @ jquery.js:4
(anonymous) @ ajax-filters.min.js?ver=1.32.3:1
dispatch @ jquery.js:3
r.handle @ jquery.js:3
trigger @ jquery.js:3
a.event.trigger @ jquery-migrate.min.js:2
triggerHandler @ jquery.js:3
(anonymous) @ ajax-filters.min.js?ver=1.32.3:1
each @ jquery.js:2
each @ jquery.js:2
(anonymous) @ ajax-filters.min.js?ver=1.32.3:1
dispatch @ jquery.js:3
r.handle @ jquery.js:3
load (async)
add @ jquery.js:3
a.event.add @ jquery-migrate.min.js:2
(anonymous) @ jquery.js:3
each @ jquery.js:2
each @ jquery.js:2
ra @ jquery.js:3
on @ jquery.js:3
bind @ jquery.js:5
a.fn. @ jquery-migrate.min.js:2
(anonymous) @ team.min.js?ver=1.4.3:1
(anonymous) @ team.min.js?ver=1.4.3:1
(anonymous) @ team.min.js?ver=1.4.3:1
ajax-filters.min.js?ver=1.32.3:1 error:

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