3/5/2018 Update - This issue is FIXED as of today and the release of 2018.300 and 2018.305. Please see the release notes for more information.
Until further notice, only Crystal runtime service packs up to and including SP20 are supported. SP21 and SP22 of the Crystal runtime engine will BREAK Report Runner. You will get no message; it simply will not start.
SAP made a major change to these two service packs (and later), and it will require a core modification to our software to support it. We are working on it, and we expect it will be 1-2 weeks.
If you are a Sage customer, it seems they have a new release that requires SP21 or later. If you have Report Runner on the same machine, again, it will break Report Runner. Until we finish our update, you will either need to hold off on the Sage update or run Report Runner on a different machine.