Why do the insides of letters fall out when I cut?

The three ways out

• Engrave the lettering instead of cutting it. The counters stay because nothing is cut through. This is what you want on a name tag, a plaque or a coaster.
• Use a stencil font, where every counter is already joined to the outside by a bridge.
• Add your own bridges: draw a small rectangle across the gap and weld it to the letter, so the counter is part of the same piece.

How to see it before you burn it

MakerWizard's check reports this as an island: a cut shape sitting inside another cut shape. It also finds the related failure, a part joined to the body by a neck thinner than 1 mm, which survives the cut and snaps later.

Both are worth a look on any file with lettering in it, including files bought from a marketplace.

Script fonts need one more step

Joined-up lettering overlaps itself. Cut as it comes, each overlap is a separate closed shape and the laser burns the same line twice. Weld the letters into one outline first; MakerWizard does this automatically wherever it sets type.