In life and in workplaces I‘ve noticed a very common anti pattern that pops up from time to time. And I‘m pretty sure I‘ve been on the offending side as well. Imagine you are an employee in a pet store that has too many cats.
Me: Oooff, i'm so swamped reaching out to all of these potential cat owners to try to verify if they are still interested or capable of owning a cat.
Coworker: Worry not, for while I also have a lot to do I will definitely help you, send me some of these fine potential cat owners and I will call them.
[a day goes by]
Me: Hey did you contact them?
Coworker: I was just too swamped! I'll get around to it, did you have their contact details btw? I seem to have misplaced them...
[This cycle continues until finally you have had enough and just contact them yourself or welcome the sweet release of death]
This pattern (once you start looking for it) pops up in literally all jobs (and relationships) i've ever had. And again, I'm pretty sure i've been the (decidedly unhelpful) coworker a few times myself. But offering to help is not the same thing as being helpful. The coworker has in fact added work for the person who was trying to offload their work, because they now have to make sure coworker is actually doing it.
Generally the coworker is not malicious, offering to help to look good in front of the boss and then blatantly ignoring doing the actual work. The coworker is usually a good person with the best of intentions that truly wants to help you, but they've just taken on too much and drop the ball on things which are not their main tasks. And if you are that coworker then you are probably also slow to realize (I was) that you are actually hurting more than you are helping.
Look out for this pattern and be sure to explain (as kindly as possible) to your helpful coworker that if they don't have the bandwidth to help you, then not offering is actually the real act of kindness.