Adding on to the issue, I found that my Farmers are only able to farm beetroot or wheat, and not potatoes (haven't tried carrots). @Axion Nineseven Player , all my Farmers have one bed which they can path to and sleep in, and in addition, one composter each. Only those Farmers with a beetroot farm are able to farm and replant, whereas those with potato farms can only replant but not farm. For reference I am using this farm design: https://www.youtube.com/watch?v=imdB0i_7tiM&list=WL&index=7&t=0s . The wiki has no mention on the effect on bed numbers on farming, maybe someone can look into the code and settle it once and for all?
ISSUE FIXED as per MCPE-47166 in release 1.13.0.