With VWX 2018 SP4 (build 435714), the align and distribute objects dialogue fails to properly distribute spotlight symbols.
In this screen shot:
blue lines are aligned on center with the furthest left and furthest right spot light symbol
blue lines are distributed with "spacing"
spotlight symbols are also distributed with spacing, but spacing between symbols is inconsistent.
I thought I was crazy, but I exported this file back to VWX 2017 and it works as expected, e.g. spot light symbols distribute evenly just like the lines.
I feel like this bug has existed through most of the life of 2018, but I've never had a chance to narrow it down.