All yield values in a month must have the same interval.
To fix the error we recommend to upload the yield files again (either via FTP or via manual upload)
This requires deleting the available yield data of the particular day first in Check and revise yield data Manual entry of yield values.
For the upload interval (not for the interval of the yield data) please select at least one hour. At shorter intervals, it is possible that the data will be overwritten.