Looks like a bug to me.
data.frame(COL = data.table::as.ITime('12:00:00')) #> V1 #> 1 12:00:00
Created on 2020-08-16 by the reprex package (v0.3.0)
Looks like a bug to me.
Created on 2020-08-16 by the reprex package (v0.3.0)