We're on hosted on ACC v7 build 8894. For some reason, when I go to the Home tab and click on Monitoring, I can't seem to view the web (web@default), mta (mta@default) etc. logs for the previous days. It shows the logs for the current date but not for any other date range I select using the date pickers there.
Are there any other iterations of the web@default or mta@default such as web2@default? The log files are only configured to hold so much information before they roll over. In those cases you may have an mta2 or web2 set of logs for the older log files. Depending on how active the environment is, these logs may only be for a day or so. Additionally when you change the date filter, did you refresh the search?