Unnecessary "Contribute Error"

Platform, device version and operating system:
PC/Steam, Windows 7

Screenshot or image:

What you were expecting to happen, and what actually happened:
I expected to be able to donate to a different task than my guildmate had donated to without getting a Contribute Error. And… I couldn’t.

To preface, this error does not cause any loss (or gain) of rewards, it is just a minor, persistent annoyance.

How often does this happen? When did it begin happening?
This has been happening for a while now (nearly every week for me), but I only just tested this specific interaction, which makes it all the more annoying.

Steps to make it happen again
I have two accounts in this guild.
If I donate to any task with one account, the other account cannot donate to any task until some time has passed (1 min? 30 seconds?) otherwise, I get the above error. This is regardless of the correct amount being displayed in the task on the second account when I entered the screen.

This is generally characterized by me completing a legendary task on one account, entering the guild menu with the second account, observing that a new legendary task has correctly been started with 0 gold contributed, donating to the new legendary task, and then being told that “Another member has contributed to this task and the amount to to be contributed has changed”. They didn’t, and it has not.

This last time, I finished Yellow 10 and Brown 10 tasks on one account, not touching purple, currently at 9/12. I exited the guild menu on the first account. I then entered the guild menu on the second account (also observing that both yellow and brown were now correctly on task 11, so the gold I had donated on my other account was recognized). I attempted put in 750,000 into Purple to finish 9 and 10. Nope, contribute error, because I donated to a completely different task on another account.

The simplest way to reproduce this is to donate any amount to any task one one account, and then, within a short period of time (but after the first account finished donating), enter the guild menu on a second account in the same guild and attempt to contribute any amount to any task. Note that despite your tasks all displaying the correct amount, you will be unable to contribute. If you wait a bit while staying on this same screen, you will be able to contribute. If it were an actual contribute error (eg., you entered the screen, a different member donated, and you are showing the wrong amount on the task), it requires this screen to be refreshed in some way before allowing the contribution (you can refresh the screen by successfully donating to another task, or simply exiting and reentering the guild menu).

Yes, I know this is just a byproduct of the system in place to prevent gold donations from being eaten and is probably not that high of priority, but I felt it should be documented nonetheless. The universal lockout timer seems arbitrary to me if the amounts are getting checked, which it appears they are.