Customer getting http request blocked in Forge app dashboard gadget config screen

I’ve built a Forge app that is a dashboard gadget. I have a couple customers testing it. The 1st customer has no issues, but the 2nd customer started getting this error this morning: Mixed Content: The page at https://xxxxservices.atlassian.net/jira/dashboards/10021/edit was loaded over HTTPS, but requested an insecure frame http://1b7aj0n-82xodlx3o-1qk9l015m9--tc7zoa-r14kyz2wv-exi3zw240.cdn.prod.atlassian-dev.net.x.51de6ab4019e404ff10ad690ab5a9d1f4ba6.d0452480.id.opendns.com/s/malware.opendns.com/?X-OpenDNS-Session=aa51dc5c0ccc5aad4_51de6ab4019e404ff10ad690ab5a9d1f4ba6_ccb9bdd6fce6bbb3b09667d77092946cdc9da836_url=1b7aj0n-82xodlx3o-1qk9l015m9--tc7zoa-r14kyz2wv-exi3zw240.cdn.prod.atlassian-dev.net%2F69bdd05a-455b-454a-ab7f-264f0e0b21b0%2F700e6d25-1ceb-45bf-b76c-948ea5b57056%2F21399339-b4b7-4f34-acf7-36d2779605be%2Fmain-resource%2F_hostname_xxxxservices.atlassian.net&server=chi3&prefs=&tagging=&nref This request has been blocked; the content must be served over HTTPS.

Gadget worked great yesterday.