Hmmm. The White Labs yeast had an expiration date of January 2022, but it did take more than 36 hours to even start bubbling.Poor attenuation is usually a wort issue or a yeast issue. How fermentable was the wort (recipe), how long and hot of a mash, how young and healthy was the yeast, how was the yeast handled, what temp was the yeast pitched at...and so many other factors. You might be able to point a finger at one thing or another or it could be a whole combination of little issues.
The wort should've been plenty fermentable (see the recipe, you tell me). My process was consistent with the usual, allowed the yeast to reach room temp, pitched when wort was close to ferm temp, but ah!
Just after pitching (67F) the fermenter went down to 62 or so, apparently due to thermal lag between the sensor and the fridge. That corrected itself in 12 hours, and I attributed the ling yeast lag to that. Maybe I injured them??