Final graavity readings

So I have brewed a few batches now and all 3 never really got to the final gravity they were supposed to. The all stopped a little short. My last bat h was a Munich Helles. Starting gravity was 1.052. Recipe called for 1.045-1.050. Waited 4 weeks in fermenter and it stopped at 1.024.
My question is what could be the likely issue. I am sure there are numerous things that can probably cause this but was wondering if maybe there is something that is Limey the cause.

Are you using a hydrometer or refractometer to take your readings? If the latter, are you doing the required correction?

Are you making yeast starters?

Likely causes would be under-pitching the amount of yeast needed; fermenting at too low a temperature for the yeast or lack of oxygen in the wort.

How much (and what kind of) yeast did you use? Did you aerate your wort before pitching? What was the temperature you stored it at vs. the recommended range?

Calabrated your hydrometer for temps? they are to read 1.000 at 60F and are +.002 at 77F I think. Also do they taste sweet? at almost +.010 they should taste sweet, or maybe you have lots of unfermentables?

I am using a hydrometer

I used Brewferm lager yeast at 57 degrees. That was as cold as I could keep it.
I did not use a yeast starter just rehydrated it from the package.

Yes I aerated it. At least I think I did a good job aerating it.

The temp is on the higher end of the range given so if anything it should have fermented more aggressively. Also it is a high attenuating yeast so I don't think that would be the cause.

What about calibration of your hydrometer? Do you have some plain (preferably distilled) water stored in the same spot as your beer? If so, take a measure of that to find what your adjustment would be and apply the same to your beer's gravity.

Never did a hydrometer adjustment. Didn't think I had to do anything with it. I do have some distiller water in the pantry that I use for my humidor. Not in same place as beer though.
Is there a write up somewhere on how to do the hydrometer adjustment testing

You can go here to read about the reasons for it and print a table to adjust or here for an online calculator.