Search words like "ON" are called Stop Words, and are not included when the Signavio Search Index is created.
For more information on Stop Words, please read the Wikipedia Stop Words page.
This is because if common words are included in the Search Index, then it would be very, very large, and the time to complete a search would increase dramatically.
Therefore, Stop Words are not included in the Signavio Search Index.
The current list of English stop words used by Signavio as at December 2019, is as follows.
a an and are as at
be but by
if in into is it
of on or
that the their then there these they this to
was will with
The solution is to not use any of these Stop Words when searching, as they will return 0 results.
The workaround is to add an extra letter to the stop word, so that it can be found in the index.
Be careful not to change one stop word into another! i.e. an → and.