What is transport?
The play, stop, record, rewind and loop controls of a DAW, and the clock they drive. Plugins can read the transport state, which is how a lyrics display knows whether the song is running and where it is.
When lyrics appear frozen, the transport is usually the answer: a stopped playhead means a stationary sheet, which is correct behaviour rather than a fault.
The moving marker showing the current position on a DAW timeline. Everything time-based in a session is measured against it, which is why a prompter that reads the playhead stays accurate through rewinds and loops.
Looping a section and recording a new take on each pass, stacking them in lanes to comp from later. Every lap starts at the same point, which makes it the fastest way to gather usable options.