Did you even know that Lester has contact missions in GTAO? Well, now you do and it's probably bugged so here is a workaround.
Lester offers contact missions in GTA Online, meaning the ones that don't take long to complete and are good for quick cash and RP grabs, especially when they are boosted during the week's bonuses. As it happens, Lester's missions are boosted for the week of June 30, 2022.
In any case, Lester's contact missions are triggered by calling him and requesting one. However, you might see that they are locked and the game only says Lester will contact you when he has a mission available.
If you are under Rank 14, you won't be able to start one at all. If you are above it and it's still locked, the missions are bugged because of weird interaction with Lester's first heist. This only happens if you have a high-end apartment from which you can launch heists.
To unlock Lester's missions, you need to complete the Fleeca Job precursor that has you scoping out the bank and then picking up the gear that Paige Harris is holding. After that, Lester will be able to offer you contact missions.
If you are high rank, have already completed Fleeca Job, and possibly other apartment heists, but the missions are still locked, you will need to call Lester, request to replay the Fleeca Job heist and wait until he gives you the green light, at which point an H should pop up on your apartment. At that point, you need to call him again and cancel the Fleeca Job. Wait a little bit, call him again and the contact missions should be available.