I know of 4 people (one of my alts) and 3 others who know for sure they used my referral and none of them showed up as a referral. The devs said this is a known problem and nothing they can do about it now but allow you to specifically choose a referral for a week.
It's hard to get some of the higher buildings without upgrading storage pretty high due to the caps, so if you are saving up make sure you check your storage limits, but you have at least 24-48 hours before you are at risk of an attack, so it's pretty safe to save up.
Keep in mind though today's daily is 5% heist and 5% daily, so depositing Drugs is five times more rewarding than normal.
Yeah, I have been upgrading my silos for when battles are re-enabled. Guess that's lucky, because the bigger building require HUGE amounts of resources.
Depositing drugs doesn't pay off that well compared with keeping them normally to upgrade a building, so I wonder how much it will help now with the bonus.