On our day of arrival 3/20 we want to take the YellowBus -Blue (we have a 48 hr pass) to Praca de Espanha (near Gulbenkian Museum). The on-line ticket purchasing doesn't work right now. Can we expect long lines at about 2-3 PM (on Mon 3/20) ? ( The Gulbenkian is the only Museum not closed on Mondays. On Tuesday 3/21/ we're doing the other sites which are closed Mondays.)
I don't know about crowds on Monday's but it's off season and school groups usually visit in the morning so I feel it will not be very crowded. On my last visit to the Gulbenkian, I went on a Sunday on which there was free admission and found it to be busy but not crowded. And there's a very nice cafeteria.