wrong summary of mean/best pace for a running activity

It seems like the data of some of my running activities are not summarized correctly. While I see the pace for some of the kms correctly in the listing (pace of each km), the best pace shown in the activity summary is a different and a much slower one (I am not talking about the mean pace dispayed there also). it differs in almost a minute. Do you have an idea on how this can be resolved? Thank you.