Same thing here happens to me. Manual works fine, along polyline, NOPE.
This issue is already reported to the development and they are actively working on it.
We have found that the numbering also does not work with alignments - Measure alignments. It will work with individual stations and offsets though. Just cannot handle automated multiple points.
Happy days! SP1 installed today seems to have fixed the problem. Starting point numbers are held and automatic placement will keep the numbering consistent. Thanks!