Genesis 30:22 contains a phrase that is easy to read past: "And God remembered Rachel." The word "remembered" — zakar in Hebrew — does not suggest God had forgotten. In the Old Testament, when God "remembers" someone, it means he is acting on his prior commitment to them, moving into involvement. Rachel had been waiting while her sister bore child after child. The waiting was not divine indifference. It was the interval before God moved. This does not answer why the interval happens. But it names it as an interval, not an abandonment.
Isaiah 54:1 was addressed to Israel in exile — a nation without land, without temple, without the external markers of God's favor. The call to sing is addressed to the barren, the desolate, the one who has not borne a child. The promise is not that the specific longing will be met in the specific way desired. It is that desolation is not the final word.
Commentary is from a charismatic Protestant perspective, drawing on KJV text and public-domain sources including Spurgeon, Andrew Murray, and Matthew Henry.