Whenever you load into patrol or an activity, reloader mods do not work as intended and have no effect at all on reload speed
The only temporary solution I have found is to remove the reloader mods and re-apply them. The can be done quickly using loadouts but it is rather inconvenient.
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It seems to affect more than just reloader mods. It has also affected reserve and scavenger mods. I'm guessing it might be affecting targeting mods as well but it's a little difficult to tell. I hope Bungie sees this and addresses the issue as well.