Despite a feverish push from developers, accountants and law firms, investors are hesitating before jumping into Opportunity Zone funds, according to wealth advisers. Devin Redmond, a 41-year-old property investor, said he had decided not to put $400,000 in capital gains from selling his San Francisco condo this year into an Opportunity Zone fund.

“You have to have a really compelling investment,” he said, citing uncertainty over what a fund would actually invest in and the long, 10-year lockup period for tax-free returns. Mr. MacDonald also acknowledged that there wasn’t “Much time” for “Extra due diligence” on the Opportunity Zone funds, and he hasn’t put any clients into the funds yet.

A database for Opportunity Zones, saw only 88 funds seeking to raise a total $26.4 billion as of April 1. The single largest is commercial real estate firm CIM Group’s $5 billion fund, followed by hedge fund firm Skybridge Capital with $3 billion and property developer Decennial Group with $1 billion. Another risk, say wealth advisers, is that people might invest too much in the fund and not set aside enough cash to pay their postponed taxes in a lump sum.