Copycat says Select a precomp
The tile or Pick list has no usable source to show. Clicking Copy gives Select a precomp layer or a comp. Select a precomp layer in the active composition or a comp in the Project panel, then hover the tile again or reopen Pick.
An open composition is only needed for copying Timeline layers. Project panel comps can be copied without one.
Copycat says Not a precomp
The click message is Select a precomp layer. The selected Timeline layers have no comp sources, and Copycat did not find selected Project panel comps to use instead. Select a precomp layer, rather than footage, a solid, text, or a shape layer.
Copycat says Locked
The click message is Selected precomp layers are locked. Unlock the selected precomp layers and retry. Locked precomp selections also take priority over Project panel comps, so clear those layer selections if you intend to copy project items.
If the selection includes unlocked precomp layers, Copycat copies those and reports N locked skipped for the locked ones. It does not unlock the original selected layers for you.
My copy still changes the original
Check the depth. 1 level keeps every nested comp shared. In Pick, unchecked nested comps stay shared. Use All or check the parts that need independence.
Footage and solid sources stay shared even with All. Layer effects and text edits inside copied comps are independent; edits to a shared footage or solid source affect both versions. The source and expression rules explain this boundary.
The wrong comp was copied
Selected Timeline precomp layers take priority over selected Project panel comps. Deselect the precomp layers, including locked ones, before copying Project panel comps.
The hover preview refreshes on entry rather than tracking selection continuously. Move off Copy and hover again before using its count to review a changed selection.
No layer appeared in my Timeline
Project panel copying creates project items only. Alt-clicking a Timeline precomp uses Copy in place, which replaces its source while keeping the layer count unchanged. Click without Alt when you want a new layer above the original.
A copied expression still points at the original
Copycat retargets literal comp names only inside copied comps, and only for comps copied and renamed in that same tree. Computed comp names, references outside the copied tree, and unchanged nested names need review. Identical original comp names are ambiguous. See the expression rules.
Review the expression in After Effects and point it at the intended copied comp. The retargeted count reports expressions changed, not a guarantee that every dependency is independent.
Pick is closed and clicking the chip does not change depth
Clicking a closed Pick chip reopens Unique copies. To change directly to another depth, right-click Copy or the chip and choose the desired option. Close the list with its Done checkmark or click outside it.
I cannot find the copies
By default they are inside a <source comp> copies folder in the same Project panel folder as the original top comp. Repeated copies reuse that folder. With The original’s folder, nested copies may be spread across their originals’ folders. Check Settings.
Copycat reports Not done or could not finish
Read the accompanying error toast. Copycat could not finish is the fallback when no more specific message is available. Inspect the project before retrying, since an unexpected error may happen after some items were created. Use After Effects’ undo history to reverse the Copycat action if needed, then reselect the intended source and try again.