But I rejoiced in the Lord greatly, that now at the last your care of me hath flourished again; wherein ye were also careful, but ye lacked opportunity.
But, х de (G1161)] - transitional conjunction. 'Now' х eedee (G2235)] is used to pass to another subject.
In the Lord - the sphere of Christian joy.
At the last, х pote (G4218)] - he was expecting their gift, not from selfishness, but as a "fruit" of faith to "abound" to their account (Philippians 4:11; Philippians 4:17). Though long in coming, owing to Epaphroditus' sickness and other delays, he does not imply their gift was late.
Your care of me hath flourished again, х anethalete (G330)] - 'ye have flourished again (as trees sprouting again in spring) in your care for х huper (G5228)] me.'
Wherein ye were also careful - for which (reflourishing, namely, the sending of a supply to me) ye were also (all along) careful.
But ... - from want of means or a messenger. Your "lack of service" (Philippians 2:30) was owing to your having "lacked opportunity."