Error is:

{
    "error": {
        "code": "missingparam",
        "info": "The \"wikilambdaload_zids\" parameter must be set.",
        "*": "See https://wikifunctions.beta.wmflabs.org/w/api.php for API usage. Subscribe to the mediawiki-api-announce mailing list at <https://lists.wikimedia.org/postorius/lists/mediawiki-api-announce.lists.wikimedia.org/> for notice of API deprecations and breaking changes."
    },
    "servedby": "deployment-mediawiki11"
}

Change 961820 had a related patch set uploaded (by Jforrester; author: Jforrester):

[mediawiki/extensions/WikiLambda@master] ZObjectEditAction: Use getTitle() not getPageTitle() to get the target page

https://gerrit.wikimedia.org/r/961820

Change 961820 merged by jenkins-bot:

[mediawiki/extensions/WikiLambda@master] ZObjectEditAction: Use getTitle() not getPageTitle() to get the target page

https://gerrit.wikimedia.org/r/961820

Checked in beta - works as expected.

Testing notes to Verify in Production:
✅ DONE (wmf.29) - check Implementation, e.g. https://www.wikifunctions.org/view/en/Z10271 (in wmf.28 works as expected)

• check Edit mode
• Tests should be ok in both Read and Edit mode (currently in Edit mode tests fail with Tester API call was nothing: http)