null showing in tooltip underline

Using the pro version, on *some* keywords instead of underlining it, it shows “null” and the tooltip.

For example, the text might read:

this is the text containing the keyword

And I put in the keyword of “text” and it would show:

this is the null text containing the keyword

Where the “null” is underlined and contains the tooltip of the word, “text”.

https://www.ads-software.com/plugins/bluet-keywords-tooltip-generator/