Originally Posted by Zorak

That was my initial reaction too, but this is slightly different -- upon rereading it a second time, my understanding is

1. paid $100 for something from LH -- it sounds like this did NOT qualify for the $300 travel credit, probably because it had been exhausted for the year and hadn't been reset yet.

2. due to cancellation OP was due a $100 refund

3. LH dragged its heels, OP contacted Chase who reversed the original $100 charge

4. LH finally got around to issuing the refund

Somewhere between 2-4, the annual travel credit reset and became available again.

5. Chase noticed the refund and therefore reversed the reversal from (3)

This is different from the usual, "I bought something, got the travel credit, then returned the thing, so why didn't the credit get reversed" situation; RNE is observing is that the reversal of the reversal, qualified for the current year's travel credit.