The Solow paradox is real, but there's another factor: most current AI tools are glorified autocomplete. You still have to prompt them, check their work, and integrate their output into your workflow.
The real productivity gains will come when AI runs autonomously - handling tasks without constant supervision. Think email triage that just happens, schedules that self-maintain, follow-ups that occur automatically.
Right now we're in the "AI as fancy search" phase. The jump to "AI as autonomous assistant" is where the productivity numbers will start showing up.