Plague Bearer - Integer Overflow

https://imgur.com/ZYJYYoX
https://imgur.com/edpOuJn
https://imgur.com/npC17gq


As per both images above, sometimes Plague Bearer seems to overflow on Stored Poison, making it unable to cast Plague Nova until I de/re activate the skill on skill page to reset the counter.

If I keep on attacking with other skills, the number seems to change, but won't go back to 100%.