When opening the "Conditional Formatting" dialog in Zoho Sheets and clicking on "ok", nothing happens. Instead, two errors appear in the console:

error { target: Window, isTrusted: true, message: "Script error.", filename: " https://js.zohostatic.com/sheet/Dec_28_2018_3_1979055/appsheet/Views/OWNER/initmin.js", lineno: 0, colno: 0, srcElement: Window, currentTarget: Window, eventPhase: 2, bubbles: true, … } initmin.js:15:995

TypeError: t is undefined initmin.js:6:2933
    e https://js.zohostatic.com/sheet/Dec_28_2018_3_1979055/appsheet/Views/OWNER/initmin.js:6:2933
    c.fn.replaceParams https://js.zohostatic.com/sheet/Dec_28_2018_3_1979055/appsheet/Views/OWNER/initmin.js:6:2857
    h https://js.zohostatic.com/sheet/Dec_28_2018_3_1979055/appsheet/Views/OWNER/defermin.js:30:2764
    t/< https://js.zohostatic.com/sheet/Dec_28_2018_3_1979055/appsheet/Views/OWNER/defermin.js:193:973
    trigger https://js.zohostatic.com/sheet/Dec_28_2018_3_1979055/appsheet/Views/OWNER/gridmin.js:84:2071
    onreadystatechange https://js.zohostatic.com/sheet/Dec_28_2018_3_1979055/appsheet/Views/OWNER/gridmin.js:84:1449
    onreadystatechange self-hosted:974:17
    process https://js.zohostatic.com/sheet/Dec_28_2018_3_1979055/appsheet/Views/OWNER/gridmin.js:83:823
    receive https://js.zohostatic.com/sheet/Dec_28_2018_3_1979055/appsheet/Views/OWNER/gridmin.js:83:600
    S https://js.zohostatic.com/sheet/Dec_28_2018_3_1979055/appsheet/Views/OWNER/gridmin.js:82:1223

It seems like dialogues do not work in Firefox