Double check your posture and form at the start of each practice and check in with it throughout. Forearm placement, neck up, left hand behind the neck for round finger shapes on fingertips, etc. Learn to be checking in for the correct feel of these aspects instinctively or habitually by repeatedly reinforcing them and keying in on the click of how they feel right when you nail them.
Make chord shapes in the air and drop all fingers at once, no fidgeting, before or after placement. If you miss one or more target frets lift all fingers between beats to quickly reset. The goal should be feeling positive fingertip engagement with the strings after pressing down each shape.
Work on chord exercise and 8th note page.
8th notes are counted like this, “1 and 2 and 3 and 4 and” where the, “and” beats fall in between the quarter note numbered beats you’re already accustomed to playing along to the metronome. This means the extra 8ths notes are playing in the spaces between (in case we haven’t covered this).
Either take turns with one person only playing uke and the other only singing, or record yourself playing the uke parts you’ll sing to (8th note stuff this week), then sing to the recording. This way you’ll be able to get separate practice doing each element before combining them.
Work on trying to get on track with your singing closer and closer to the beginning of each run, gradually expanding on how well you’ve been doing towards the end once you lock on. Focus on replicating the feel and sound of being on track more consistently so you can do it right from the start eventually.