Original Post — Direct link
So if you use "Pestilence", stack some shots on target and change a weapon. "Pestilence" stacks do not deal any damage to enemy.
Even if you change back to "Pestilence" damage per tick still wouldn't proc and you have to stack it again.
Additionally after shooting from pestilence on infected target stack will vanish and game will count, like there were none.

Steps to repeat this bug. (If you are an ordinary player you can repeat it and say, do you have it too.

  1. Use Pestilence LMG
  2. Shoot a target/enemy to see multiple stacks
  3. Change pestilence on any other weapon (AR in my case)
  4. Target still has plague stacks, but no damage dealt to target.
  5. Change back to Pestilence (At this point damage from plague won't resume ticking)
  6. Shoot target with stacks before they expire to add stacks or refresh duration.
  7. BUT, number of stacks of plague on target will start from 0 no matter how much stacks were on it.

Here comes some low quality audio-less video demonstration. I am ready to provide additional information/help if required.

(Shooting range)
Spoiler:  Show

(Field, but numbers are barely visible.)
Spoiler:  Show
over 4 years ago - Ubi-Mark. - Direct link
Hello Agents,

Thank you for bringing this to our attention! I passed your videos along with your desctription to the development team for further review. Apologies for any inconvenience caused by this and if you have any additional questions, please let us know.
over 4 years ago - UbiExcellent - Direct link
Hey guys! This behavior is intended; You lose the benefits of your weapon talent (or exotic weapon talent) if you swap to a different weapon. This is intended not just for Pestilence, but all weapon talents and weapon exotics. There are only a few exceptions to this rule if the talent explicitly asks you to swap weapons to activate it (Finisher), if it provides a group buff (Vindictive), or has a cooldown that needs to be tracked (Future Perfect). Please feel free to post any feedback or suggestions you have about this, and I'll be happy to forward them to our dedicated teams.
over 4 years ago - Ubi-Borealis - Direct link
Hey there Alexs410!

Please refrain from bumping posts, as this goes against our forum rules.

I apologise for the delayed response. We recognise that the stacks should be removed at the same time as the debuff, and that this does appear to be a visual glitch. The development team is investigating this issue further, so thank you for reporting this.