Can you open the JavaScript console (instructions on various browsers can be found here), then observe what errors you see when you are assigned to a Jira ticket or when someone comments on your assigned issues?
Which browser or desktop app have you reproduced this on?
What is the version of your JIRA instance? (you may need to ask your Jira Admin if you’re not one yourself).
Unfortunately not getting any errors from Mattermost javascript console, really no messages at all when I assign or comment an issue to myself in our Jira instance.
However after configureing the webhook by our jira admin I am seeing these types of errors, which is odd to me, does it need a team name in the request uri?
{"level":"error","ts":1567766404.6050675,"caller":"mlog/sugar.go:23","msg":"ERROR: ","plugin_id":"jira","Status":"400","Error":"Request URL: no team name found","Host":"REDACTED","RequestURI":"/plugins/jira/webhook?secret=REDACTED&user_id=michael.vanes&user_key=michael.vanes","Method":"POST","query":"secret=REDACTED&user_id=michael.vanes&user_key=michael.vanes"}