I am unable to trigger the swimming animation with a single water source block, whether that’s in a one block deep lake or attempting to trigger the swimming animation for a tiny home entrance. The only way it could be done was by putting two source blocks on top of one another.
Thank you for your report!
We're actually already tracking this issue at MCPE-58953, so I will resolve and link this ticket as a duplicate.
That ticket has already been resolved as working as intended, which means this is not considered a bug and won't be fixed. Please do not leave a comment on the linked ticket.
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