Could be the type of solder you are using, if you use non-lead solder the pump has issues picking it up. Again you can use a desoldering wick over the pump as well. The pump I used wasn't as small as some of the YT'ers that I've seen (Tenma Desoldering Pump - looks like a Hakko manual pump) and I have minimal issues since iKBC used lead based solder on the board I desoldered - only issues I ran into was the butane based iron I was using from Snap-On (works well in a pinch since I used it for automotive reasons - stays in my mobile tool kit for when I go trail riding/overlanding).
The pump I used:
(https://90a1c75758623581b3f8-5c119c3de181c9857fcb2784776b17ef.ssl.cf2.rackcdn.com/0419316_719120.jpg)