'Default envelope point shape' issue

[audio2u]

Hi all,
Apologies if this has already been addressed elsewhere, but I just noticed (I'm currently running v5.70, the latest release as of today) that even though you can set a default envelope point shape under 'Prefs/Project/Track-Send defaults', the tempo map of the master track will ALWAYS default to Square, even though point shapes for THAT track can be either Square or Linear.
I tried setting the Track-Send default to Linear, but the Tempo Map still insists on creating every point as Square.