If CreateMissing is run to add new archive data from monthly logs files the first date in the first log file is ignored and not added to the dayfile. For example, if I have new data for the full month (1st to 31st) of Jan 79 in Jan79log.txt and have the start date in Cumulus.ini set to 31/12/1978 CreateMissing doesn't add 01/01/1979 to the dayfile, which starts from 02/01/1979 after the run. I also tried this with data for Nov 2022 in Nov22log.txt and 01/11/2022 was also missing from the dayfile so it's not just very old data that causes this problem.