A trust that owns nothing does nothing.
People arrive believing the hard part of an estate plan is the drafting. It is not. The drafting is the part with the most pages and the least risk.
A revocable living trust is a set of instructions attached to a container. Signing it creates the container. It does not put anything in it, and nothing about the signing ceremony suggests that a step is missing.
Funding is the work of retitling what you own so the trust owns it. The house needs a new deed recorded with the county. The accounts need the trust named as owner, not as beneficiary, unless there is a reason to do otherwise. The business interest needs an assignment that the operating agreement actually permits.
Each of those is a separate act with a separate piece of paper, and each of them can be quietly skipped without anything appearing to go wrong for twenty years.
An asset the trust does not own goes through probate, which is the exact thing the trust was bought to avoid. In California that is a public proceeding, on a statutory fee schedule, and it commonly runs a year or more.
The cruelty of it is the timing. Nobody discovers the omission while it can still be fixed in an afternoon. They discover it in the month after a death, when the person who could have signed the deed is the person who has died.
Ask for the list of what the trust owns. Not the schedule attached to the back of the document, which is a wish. The recorded deed, the account statements showing the trust as owner, the assignment for the business interest.
If nobody can produce that list, the plan is a document rather than a plan, and that is a fixable problem right up until it is not.