Custom sidebar groups exist in data but don't render in sidebar (Code tab)

Description:

Custom sidebar groups created on one device (via the app UI on a separate PC, "Zen") are not appearing in the sidebar on a second PC, even though the underlying data confirms they exist and are correctly assigned.

Environment:

• OS: Windows 11 Home Single Language, build 10.0.26200
• Affected device: secondary PC (not the one where groups were originally created)

Steps to reproduce:

1. Create custom sidebar groups on Device A (Zen) — in this case: rendimiento computadores, audio, video.
2. Open Claude Code on Device B, same account.
3. Sidebar only shows a "Sin grupo" ("Ungrouped") section; no group sections render, even after scrolling.

Troubleshooting already done:

• Confirmed via API (list_groups) that all 3 groups exist with correct ids and session counts:
• cg-a4bdf6df-28e9-441b-894c-36d822bf9167 — "rendimiento computadores" (1 session)
• cg-11472a53-5bca-46ea-b958-4e356657c52c — "audio" (1 session)
• cg-344739b5-cc31-4984-ac7b-c9c5bae542b9 — "video" (0 sessions)
• Confirmed via API (list_sessions) that the grouped sessions exist locally on Device B and carry the correct group field (e.g. session "sincronizar equipos" → group "rendimiento computadores"; session "ajuste de audio" → group "audio").
• Confirmed sidebar view settings on Device B are already group_by: "custom", status: "active" — correct configuration for groups to display.
• Fully killed and restarted the app process on Device B (not just closed the window) — issue persists.

Expected behavior: Group sections for rendimiento computadores and audio should render in the sidebar on Device B, containing their respective sessions.

Actual behavior: No group sections render at all; grouped sessions are simply missing from view (they don't appear under "Sin grupo" either, since they're correctly excluded from that bucket).