Groups - Group Profile - Counts and member lists are not as expected and not even constant for a session

Environment

NoUpdate 7.1.11.11074622243 (64bit)
Release Notes

You are at 147.9, 78.0, 50.8 in LindenWorld B located at simhost-01ce390e7073327d2.agni
SLURL: http://maps.secondlife.com/secondlife/LindenWorld%20B/148/78/51
(global coordinates 237,972.0, 244,302.0, 50.8)
Second Life Server 2025-02-07.13191265457
Release Notes

CPU: Intel(R) Core(TM) i7-3770K CPU @ 3.50GHz (3605.65 MHz)
Memory: 32712 MB
OS Version: Microsoft Windows 10 64-bit (Build 19045.5247)
Graphics Card Vendor: NVIDIA Corporation
Graphics Card: NVIDIA GeForce RTX 2070 SUPER/PCIe/SSE2

Windows Graphics Driver Version: 32.0.15.6081
OpenGL Version: 4.6.0 NVIDIA 560.81

Window size: 1733x880
Font Size Adjustment: 96pt
UI Scaling: 1
Draw distance: 128m
Bandwidth: 3000kbit/s
LOD factor: 1.375
Render quality: 3
Texture memory: 8192MB
Disk cache: Max size 3960.0 MB (72.2% used)

J2C Decoder Version: KDU v7.10.4
Audio Driver Version: OpenAL, version 1.1 ALSOFT 1.23.1 / OpenAL Community / OpenAL Soft: OpenAL Soft
Dullahan: 1.14.0.202408091639
CEF: 118.4.1+g3dd6078+chromium-118.0.5993.54
Chromium: 118.0.5993.54
LibVLC Version: 3.0.21
Voice Server Version: Vivox 4.10.0000.32327.5fc3fe7c.5942f08

Packets Lost: 10/26,044 (0.0%)
March 07 2025 09:11:41

Description

This started with some recent complaints of group membership display still being broken:
https://community.secondlife.com/forums/topic/517096-official-viewer-and-group-members-not-showing/#findComment-2874055

There'd been some work in there so I was skeptical. But I can confirm this.

Using the 'Linden Lab Boston' group on Agni where I'm the last surviving member, basic info display shows 14 members (which might be correct but includes all the disabled accounts):

Going to 'Profile > Roles', we see 0 Everyone, 9 Officers, 0 Owners:

Showing the members of the 'Everyone' role gives nobody:

However, going to 'Profile > Members' shows me and I'm online:

Finally, going back to 'Profile > Roles' now shows a count of 1 for 'Everyone':

So there are a number of bugs in here and I expect they're in both the viewer and the servers. We'll start with the viewer and then add additional GHIs as needed.

Reproduction steps

See above.

Reproduce the inconsistent counts through the group profile's basic info, Profile > Roles, and Profile > Members views, using the Linden Lab Boston group scenario described. Start by tracing the viewer's group profile UI and its member and role data loading; compare the displayed counts and lists across the views. Done means the counts and member lists remain consistent within a session.