Yes, there was a delay in work, but not due to technical reasons. The main reasons are (1) Chinese New Year Holidays, and (2) COVID-19.
1) Workers usually take off for Chinese New Year Holidays from 2 weeks or more.
2) Due to COVID-19 spreads, the central government imposed an order that further 2 or 3 weeks holidays before any work can commenced.
3) Workers came back slower than normal because of COVID-19 related rules on transport, e.g. on all aircraft and railways, passengers must be seated at least one metre away from others. This means airliners, railways and buses only carried 1/3 to 1/4 of their normal passenger load.