SharePoint Online column formatting icons missing

Question

Sinc a week or two the icons within a quick actions have gone missing while the exact same JSON was working fine earlier.

Even using the JSON of the default mailto-icon on the Microsoft Tutorial https://docs.microsoft.com/en-us/sharepoint/dev/declarative-customization/column-formatting it shows a square:

{

    "elmType": "div",

    "children": [

        {

            "elmType": "span",

            "style": {

                "padding-right": "8px"

            },

            "txtContent": "@currentField"

        },

        {

            "elmType": "a",

            "attributes": {

                "iconName": "Mail",

                "class": "sp-field-quickAction",

                "href": {

                    "operator": "+",

                    "operands": [

                        "mailto:",

                        "@currentField",

                        "?subject=Task status&body=Hey, how is your task coming along?.\r\n---\r\n",

                        "@currentField",

                        "\r\nClick this link for more info. http://contoso.sharepoint.com/sites/ConferencePrep/Tasks/Prep/DispForm.aspx?ID=",

                        "[$ID]"

                    ]

                }

            }

        }

    ]

}

Results in: 

The debugger shows:

I have css-number where it was working: (347)

Answer 1

Hi DjangoLohn,

We are glad to help you on this issue.

I just did a test and it seems I can reproduce the issue by my side. I will write down my test result below:

1. Based on my test, when we use this “Mail” icon to be the action icon, it doesn’t show up in the SharePoint Online column. But when I hover over my mouse to the place where it should show up, it can be clicked and work well to start creating a new email to the person.

It should look like:

But it is showing nothing like below:

2. When I change the “Mail” icon to “Error” icon, it doesn’t show up either. 
3. Then I use the “mail” icon only for conditional formatting based on a number range, without adding quick action, it then can show up without issue. See below:

4. I tried several Internet browsers with incognito window, the issue persists. So the issue should not related to that.

Based on the test result above, I think, just like you said, the issue may only happen when we add any quick actions. The quick action can work well, but it make the icon missing for some reason.

For JSON questions or issues, we suggest you post them to our MSDN forum. There are the categories for such customization and programming problems. 

Thanks,

Rena