Thank you for the additional information. I can not with 100% certainty tell the root cause of the problem, but I have seen the problem and corrected it.
Project-GC uses both the corrected coordinates field and the personal cache note field when determining corrected coordinates. Most of the time, Project-GC doesn't find the corrected coordinates though, therefore the personal cache note is the most commonly used field. This is due the design of Groundspeaks API.
When coordinates exists in them both, the coordinates in the corrected coordinates field is used.
In this case, you had coordinates in both according to Project-GC. Those in the personal cache note seemed correct when I viewed them (not posting the public here). Those in the corrected coordinates field was N0 S0. Since the corrected has higher weight in our system, those were used.
Why they were 0,0 I do not know. Either, you have had those in the field for a while, or it's a bug in Groundspeaks API, or it's a bug in our side. Out of all (37.3 million) corrected coordinates known to Project-GC I notice that 326 of them are at 0,0. We will look into that.
Anyway. I have corrected the error you are having by refreshing your corrected coordinates. I understand that it wouldn't be easy for you to understand the issue, but I will write what you could have done anyway. Maybe this thread will by found by someone else in the future.
With our new self-support system, you could have asked the system to refresh the data for the specific geocaches. The self-support system can be found by clicking one of our orange support buttons, then self-support, then adding the gc-codes in the last input field, and submit.
Alternatively you could have refreshed all your finds in the self-support system as well.
You could also have added them into a Virtual GPS and built a GPX file with "refresh corrected" checked.
We are sorry for the inconvience caused and hope that it will not happen again.
UPDATE: I found that an additional 273 of your geocaches has 0,0 as corrected coordinates. I will tell the system to update the data on those since it is likely to be incorrect. It might take an hour or so.