EDIT: Can be closed, my JSON "{text:"abc123"}" is invalid  >.<

Updating properties "Text1", "Text2", "Text3" and/or "Text4" of a text sign results in the corresponding line becoming blank/empty. {{}}

To reproduce:

1. Place a new text sign somewhere.

2. Execute command

/data merge block [X] [Y] [Z] {Text2:'{text:"abc123"}'}

3. Get the response "Modified block data of [X], [Y], [Z]"

4. Notice that line 2 of the sign became blank.

5. Validate debug data (F3+I) and see that "Text2" is empty

The same happens when using "/data modify ..."