1
Diagnostic step 1
Reproduce with console and pmset -g log; capture system.log while entering sleep and waiting for the wake to capture exact kernel messages for the downstream port.
FULL AI ANALYSIS
MacBook Pro wakes from sleep within 30 seconds only when bus-powered USB‑C SSD is attached to a hub
Generated Oct 3, 2026, 12:35:03 AM
Analysis summary
pmset logs showing USB as the wake reason plus intermittent device disconnect/reconnect point to the hub/SSD performing a short reset or reenumeration that the kernel interprets as a wake event. Because the CPU/system wakes on USB device attach, the likely root causes are: the hub's power budget or cable allowing transient power drops as the system settles into sleep; the hub or enclosure performing a link training or spin-up audible event that triggers USB re-enumeration; or a macOS USB driver reacting to a non-compliant USB-C PD or USB-C Power Role change. Differences between bus-powered and externally powered hubs strongly implicate power negotiation/hub behavior.
Possible causes
Bus-powered hub or SSD enclosure draws brief surge current during sleep causing the hub to reset the upstream port, generating a USB attach event.
90%Hub or SSD firmware incorrectly implements selective suspend or U1/U2 link power states; on sleep this triggers re-enumeration.
65%USB‑C Power Delivery role or CC line negotiation changes at sleep transition, interpreted as device connect by macOS.
35%macOS IOKit/USB driver treats certain disconnect/reconnect patterns as wakeable events (OS-level behavior rather than hardware).
30%Suggested fixes
2
Diagnostic step 2
Test with a powered USB‑C hub (confirmed as working in your tests). If a powered hub prevents wake, prefer that as a workaround.
3
Diagnostic step 3
Try a different bus-powered hub of known compatibility or a different SSD enclosure to isolate whether hub or enclosure is at fault; if only one vendor reproduces, file a firmware/compatibility bug with that vendor.
4
Diagnostic step 4
Use an Apple‑certified USB‑C cable rated for higher current to reduce voltage sag; repeat sleep tests.
5
Diagnostic step 5
If reproducible and isolated to the hub/enclosure, escalate to vendor support with collected logs (system.log, ioreg, pmset output) and avoid sending sensitive data. If symptoms suggest driver-level misbehavior across multiple hubs, file a bug report to Apple with diagnostics and consider a macOS update or SMC-style reset steps advised by Apple support (documented and reversible).