What probably happened is that you died before those two times and instead of going to your grave, you reflected, while being on the other server?
If that happens, I think the old gravemarker location will not be cleared, so if you die afterwards, a new gravemarker wont appear because there already is one present. This would last until the specific server gets a reset. You can check this by using any bindstone to find out the location of your marker.
It could also be perhaps that there was a mishap when you finished reflecting, even though you were on the same server.
At any rate, best first step is to check with the bindstone. If what I mentioned isn't the case, definitely post here again.
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