Sync to Android over wifi loses & duplicates playlists

[hb5000]

I've been syncing a weekly-changing playlist from laptop to Android over wifi successfully for over a year, but in the last month it's started completely deleting it from the Android, or sometimes re-creating it incomplete in the wrong location, or appending a _1 with last week's songs in, or the new ones with some missing.

Deleting the playlist on Android and then re-syncing worked as a one-off fix today.

Deleting and re-installing stopped crashes, but it hasn't fixed the faulty behaviour. Any advice?

[Lowlander]

Which version of MMW and MMA?