Partially luck and maybe you never solved it with a DP solution. There are problems for which DP will give an answer but it isn’t a hard requirement for you to come up with it.

I’ve received quite a few DP problems in my time interviewing.

Then again, I feel like saying I’m unusual. I’ve received a lot of very difficult problems. Almost like the people are trying to set me up for failing. ;)

DP solutions were really in vogue for awhile, and seem to be asked less now. I heard a completely unsubstantiated rumor that FB found them to cause high false negatives because they're such a tricky and specific problem type. Also, once you know the "one trick" to solving them they don't help illuminate candidate thinking.

Questions with DP solutions are usually not particularly great for interviews. They usually don't have any solutions in-between brute force and DP. If somebody doesn't come up with a DP solution you, as an interviewer, just learned that they don't know DP, but it doesn't give you too much useful signal on the candidate's skills. DP is just kind of a trick that you can learn to solve this specific type of problems, but knowing the trick is not something that FAANG companies want to test for.

I tell interviewees to practice some dynamic programming problems because dynamic programming questions are the least intuitive, and it's good to be prepared in case that's what you get asked.

For the same reason though, I think they make for terrible interview questions - very much dependent on knowing a specific "trick" that doesn't actually come up often in day to day coding.