Yeast starter gravity reading

I feel like I should be past any yeast starter questions,
but I've read often that a yeast starter should be down to
about 1.010 gravity-wise when the yeast has finished its
work. I've done 5 batches with liquid yeast, always using
a starter based on recommended pitching rates.

For example, I'm brewing a sweet stout on Sunday and
started building up a starter two days ago. I started with
500 mL, using the 1 gram per 10 mL rule, so 50 g DME and
water to 500 mL. 24 hours later I bumped it up to 2 L with
150 g DME and 1500 mL water, boiled, etc. Oxygenated by
swirling whenever I pass by. I've never had vigorous
activity in a starter, but it does foam up after swirling
a day later, as it's doing now. But the gravity is still
at 1.040. Of my other 5 batches, I've only taken the
gravity once and it was 1.040 then, too, but I was making
beer that day and had to pitch it. I haven't had any
problems with my beer finishing well, but I've only made
one beer over 1.065 OG, and it did finish well.

Any ideas as to what I could be doing wrong? I'd hate to
think I'm in a habit of underpitching, not to mention
wasting DME.

you actually want to try to pitch the yeast while its at high krausen, effectively jump starting the yeast. it will still work fine pitching after they have dropped out and increased the yeast count, though. i have good luck with pitching the yeast about 18 hrs after ive made the starter.

i dont know what to tell you about your gravity issues, though.

I've pretty much been making the starter in plenty of time, so when it's been 24 hours or so after stepping it up to the volume I want, I just throw it in the fridge, take it out the day of brewing and decant off the wort.

But it's the high gravity I have issues with. Why is this happening? If I'm doing the process correctly... I don't understand. One would think this means the yeast weren't doing anything... or else the gravity would drop.