sp_BlitzIndex only results in one row (with priority -1)
V4.1 is the last working version.  It is an issue in v4.2 - v4.8(current).  It works for some databases, but not all, when run with no parameters.  For example, it works in master, but fails in a Dynamics GP company database. @Mode = 4 still works fine though.

I tested versions 4.1 - 4.8 on SQL Server 12.0.4100.1 and 12.0.5511.0