Non-reversible route near Winchester

Here is a short part of my normal route to/from Winchester

https://cycle.travel/map/journey/151307

Travelling North-South the route is fine and exactly matches the situation on the ground.  Now use the "reverse route" button.  The route takes you on a hilly 3mile detour! In the real world there is no impediment in either direction, so I assume there is some wrongly-applied "one direction" message in OSM.  It's really annoying because a lot of the many exercise rides we have ridden since lockdown go this way and I want to be able to choose freely which way round to plot.  I have no experience of editing OSM and don't wish to make this error even worse by untutored meddling!  Please help if you can.

Splitting route for PDF?

I have just plotted a 256 mile route along the Mercian Way (mostly NCN 45).  When I try to export as PDF it tells me the route is too long to export as a single PDF and asks me to split into chunks of less than 300km.  Is there a way to do this without losing all my route tweaks or will I have to start again and plot it in two sections? 

On a related topic, it would be nice to have more control over the scaling of PDF maps.  I often have to do lots of fiddling with print magnification to get a usable printed map.  Yes I know I ought to buy a Garmin, but I'm old-school and rather like paper maps ...