With most things like this lots and lots of practice will help… but I’m sure you don’t need telling that.
Perhaps try sticking some extra air in your shock and engaging any climb type modes. Just to stop your rear shock trying to absorb your attempts to weight shift and pull up.
Also do lots of wheelies, then start to try stop pedalling and hold a manual once in the balance point. Experiment with staying seated and moving to a standing position. Just to help with being comfortable in the balance point and it’s extremes. I’m a big believer in learning to wheelie is a good precursor to learning to manual.
Since you’ve learnt to manual previously this one isn’t going to be necessarily useful, but just for others reading, a nice flat surface on a slight downhill with a little something to get a little front wheel kick off of will help for practicing.
Did I mention just keep practicing 😀