I just took a quick look on your code and two things caught my attention:

1 - I think you could remove the '%' character from your regex search, since there's none on the result. (98.880000000000000).

2 - You want an alert, when the threshold hit 90%, but you're setting it to 40, so it does make sense to not generate any alerts, since the space is never less than 40 (as shown in the result you sent).

You could try removing the '%' character from the Regular Expression (regex) and increasing the threshold to 99, to see if it does pops something.

I hope this answer helps you, feel free to reach me at any time :)