Most likely cause: the Power Apps grid control (modern grid) is now
the default for your environment, and its "Allow editing" property
isn't enabled on the subgrid. The legacy "Editable Grid" table-level
toggle is overridden when modern grid is active. Try in order:
Step 1 — Confirm which grid control is bound.
Open the form → click the subgrid → right panel → Components.
Look at what's listed. If it says "Power Apps grid control" → go
to Step 2. If "Read-only Grid" → go to Step 4.
Step 2 — Enable editing on the modern grid.
Components section → Power Apps grid control → click the pencil/
gear → "Show advanced properties" → set:
Allow editing = true
Allow filtering = true
Allow sorting = true
Step 3 — Save → Publish → hard refresh.
Ctrl+F5 the app. Test the subgrid. If it now edits inline, done.
Step 4 — Swap Read-only Grid for editable.
If Read-only Grid is bound → remove it → add Power Apps grid
control → repeat Step 2.
Step 5 — Check the environment "Modern controls" setting.
Power Platform admin centre → your environment → Settings →
Product → Features. Look for "Power Apps grid control as default"
or "Modern controls". If it's on but you want classic behaviour,
you'd need to toggle off — but better fix is Step 2.
Step 6 — Check form OnLoad for JS overrides.
Form designer → Form properties → Events → OnLoad. Look for any
handler calling setControlState, setSubmitMode, or setting the
grid context to read-only. Remove or condition out.
Step 7 — Confirm at the APP level too.
In the app designer (modelapp), select the table in the sitemap →
right panel → check no "View only" override on the table entry.
Step 8 — Sanity check: which form is loading?
If the table has multiple forms, ensure the one with the editable
subgrid is the form being used (Form Order may push a different
form). Power Apps maker portal → table → Forms → check Form Order
for the security roles in play.
If none of the above resolves it, this likely needs a Microsoft
support ticket — environment-level grid control overrides occasionally
get stuck after a tenant-wide control migration and Microsoft has to
flip the flag server-side.
Hope one of these gets you back.
