+1 to Script Editor. I often have to close and reopen my scripts due to the syntax highlighting being 100% broken.
+1000 to the Asset Manager. Launching it without list view and all the bugs it had was greatly impactful to my workflow. I had to use a FFlag editor for a week before they made it beta again. I still don’t think it’s in a spot where it should surpass the game explorer. The AM just isn’t scalable for universes and decent amounts of assets yet.
+10000 to Packages and LinkedSources. Their bugs, lack of features, and lack of support has prevented (and not exaggerating here) at least 3 months of work. LinkedSources were great for universes. Packages are not.
Another feature you didn’t mention that I need for my flow is surfaces. Surfaces were deprecated, but there’s currently no easy way to tell which face of a part is front, back, top, left, right, etc. This has made some of my scripting trial and error, or going out of the way to make a part plastic, apply a surface, then check. Additionally, removing surfaces from part properties was totally not helpful. Making color and material not a dropper tool is also really annoying.
Misc stuff that’s been a big pain in my rear:
Not sorted in any order...
Haven’t bothered reporting this bug on the forum yet, but having a medium amount of assets throttles your AM/Game Explorer to the point of failing.
So many user reports from this engine problem: https://devforum.roblox.com/t/horizontal-scroll-w-mouse-wheel-breaks-camera-zoom-and-instead-tilts-camera/408643/87
User reports from this engine problem: https://devforum.roblox.com/t/dialog-dialog-responses-and-chat-cut-off-without-the-new-bubble-chat/834743
Lag, wastes my time, and plugins can’t solve this: https://devforum.roblox.com/t/dont-auto-select-descendants-of-a-model-or-folder-when-undoing-a-deletion/738324
This one is the greatest pain of recent: https://devforum.roblox.com/t/multiple-tools-in-roblox-studio-broken-when-any-plugin-is-enabled/790970/41
Rthro =/= R15, even if you lock scaling. Very gamebreaking: https://devforum.roblox.com/t/r15-rthro-combinations-break-games/317331
Makes packages a bit difficult to work with: https://devforum.roblox.com/t/toolbox-and-asset-configuration-are-not-loading-all-of-my-models/824511
Randomly happens, is really annoying: Studio no longer saves the layout of my windows
What all this really boils down to is removing a feature before the alternative is done. Don’t sunset or deprecate things until the alternative is 100% completed.