Is there a middle way between working towards personal liberation and liberation for all sentient beings?
There is no conflict, the dichotomy is false and is based on incorrect understanding. As Buddha said in Sedaka Sutta:

When watching after yourself, you watch after others. When watching after others, you watch after yourself.
And how do you watch after others when watching after yourself? Through cultivating, through developing, through pursuing. This is how you watch after others when watching after yourself.
&quot;And how do you watch after yourself when watching after others? Through endurance, through harmlessness, through a mind of goodwill, &amp; through sympathy. This is how you watch after yourself when watching after others.