Check the build first
The most reliable fix is to make sure Steam has updated Dressmaker. Two early post-release patches changed tutorial behaviour, so advice recorded from the launch build may no longer match the current flow.
Moving to the next customer
Build 403 made the bell an explicit progression step. Complete the current tutorial instruction, return to the shop state where the bell is available, and ring it to summon the next customer. Waiting without using the bell is not the current intended flow.
Sketchbook softlock
Build 410 fixed a case where opening the sketchbook before the tutorial requested the bell could block progress. If this happened on an older build, update the game and repeat the current prompt in order. Avoid applying prototype-specific workarounds to the full release.
Other official tutorial fixes
Build 403 also corrected a cursor issue and added a back button during the store tutorial. It fixed commission-state problems such as failed commissions granting money and a lace-trim tagging issue. These notes are useful because they separate confirmed bugs from an unexplained interface state.
Before restarting
Read the instruction currently shown, close any panel that is not part of that step, and try the bell when the tutorial asks for the next customer. Restarting or deleting work should be a last resort; the public patch notes do not say that save deletion is required for these fixes.