The rankings of the keywords monitored under Analysis are taken from Search Console. It should be noted here:

The Search Console only provides rankings / positions if there have also been impressions / impressions in the period under consideration!

This means that a URL of the project must have been displayed in the Google results for the keyword in question. If the corresponding results page - on which the URL would appear - is not called up by any Google user, Search Console does not provide a position. In the following example, there was no impression (red graph), consequently no position (green graph):

Furthermore, it should be noted that the last ranking results are always 2 days old: