Suggestions are not visible if changes made to a field variable

I have a document in which I have created multiple field variables. In suggestion mode if i made any changes in document they are visible as changes with words removed as striked and added as yellow font, but if I change any text in field variable which are used at 20 places, the change is not being shown. Also when converting to pdf, the changed text at other places are visible with same behaviour(removed text as striked and added text as underlined yellow font) but changed text in field varible is not visible in pdf file as well. Is suggestions even allowed on Field Variables or just on normal text?

means Show Changes ?

many gory details here : Track changes - The Document Foundation Wiki