List: Lookup Column content disappears when using conditional formatting

Hi all,

SharePoint and it pointless limitations (or bugs) drive me crazy again...

I have a list, that is used by different people. As it´s still not possible to color headers or similar, I got used to insert lines left or right of a column via conditional formatting. With such, I create "blocks" of columns for each user. Better that nothing... But now comes the kicker. 

It worked fine so far, but now with a lookup column, the content just disappears. 

This is my list without the border, numbers visible to the left.

Now with formatting applied to the left lookup column, the content is just gone.

I start with "no style" at formatting, as I only want to have the border. The teaser clearly shows, that text should be visible:

The json code has some "hidden" attributes in there, but no matter what I change, the content does not reappear.

{

"$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",

"elmType": "div",

"style": {

"box-sizing": "border-box",

"padding": "0 2px",

"overflow": "hidden",

"text-overflow": "ellipsis"

},

"attributes": {

"class": "sp-field-borderRightBold sp-field-borderRightSolid sp-field-fontSizeMedium"

},

"children": [

{

"elmType": "span",

"style": {

"overflow": "hidden",

"text-overflow": "ellipsis",

"padding": "0 3px"

},

"txtContent": "[$PA_x0020_Nr_x002e__x003a__x0020_.lookupValue]",

"attributes": {

"class": "sp-field-fontSizeMedium"

}

}

]

}

Please help... How do I get the border AND my content?

Thanks!