Glorious Alpha Two Testers!
Alpha Two Phase III testing has begun! During this phase, our realms will be open every day, and we'll only have downtime for updates and maintenance. We'll keep everyone up-to-date about downtimes in Discord.
If you have Alpha Two, you can download the game launcher here, and we encourage you to join us on our Official Discord Server for the most up to date testing news.
Alpha Two Phase III testing has begun! During this phase, our realms will be open every day, and we'll only have downtime for updates and maintenance. We'll keep everyone up-to-date about downtimes in Discord.
If you have Alpha Two, you can download the game launcher here, and we encourage you to join us on our Official Discord Server for the most up to date testing news.
Luck and Guild Luck increase

It isn't clear how luck works in general, and also how the guild perk affects luck. If it is multiplicative, then it is useless to add a couple % of luck. If a mob has a .5% chance of dropping an item, and your guild gives you 10% luck...well it now has a .55% chance...If it was 5% base, now it is 5.5%...completely useless.
This leads me to believe that the guild bonus is additive. The mob with a .5% chance would now have a 10.5% chance and the mob with a 5% chance would now have a 15% chance.
However...this does not seem to be the case in game either. The tropics is the best test of this, as getting 10% luck in a guild is probably not possible. When you go to PVP areas in the tropics, its a flood of recipes and other misc essences and emblems. THINGS definitely drop more, however it seems like the things that had higher drop chances are now "checked" first on the item drop, ultimately negating the increase in drop chance for the lower chance items that you wanted anyway.
This leads me to believe that the guild bonus is additive. The mob with a .5% chance would now have a 10.5% chance and the mob with a 5% chance would now have a 15% chance.
However...this does not seem to be the case in game either. The tropics is the best test of this, as getting 10% luck in a guild is probably not possible. When you go to PVP areas in the tropics, its a flood of recipes and other misc essences and emblems. THINGS definitely drop more, however it seems like the things that had higher drop chances are now "checked" first on the item drop, ultimately negating the increase in drop chance for the lower chance items that you wanted anyway.
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Comments
So if your odds of the drop were 0.5% ad you added 10% 'droprate bonus, I'd always expect the chance to now be 0.55%.
So, basically, I think your expectation is just wrong, those 'increase droprate' buffs are usually tiny like that, and the effect is felt 'across the server' or 'across a guild', not a thing that a standard solo or small group can say they 'notice'.