This is from EF which indicates a technical issue with the aircraft:

DOBA209/16MAR
* OPERATIONAL FLIGHT INFO * BA 209 -1 WE 16MAR22
CITY INFO HOUR (LOCAL)

FLIGHT CANCELLED 2148
TECH
*1A PLANNED FLIGHT INFO* BA 209 -1 WE 16MAR22
APT ARR DY DEP DY CLASS/MEAL EQP GRND EFT TTL
LHR 1415 WE FAJCDRIWETY/M 388 9:55
BHKMLVSNQOG/M
MIA 2010 WE 9:55
COMMENTS-
1.LHR MIA - MEMBER OF ONEWORLD
2.LHR MIA - DEPARTS TERMINAL 5
3.LHR MIA - 9/ NON-SMOKING
4.LHR MIA - SECURED FLIGHT
5.LHR MIA - ET/ ELECTRONIC TKT CANDIDATE
6.LHR MIA - CO2/PAX* 390.87 KG ECO, 781.73 KG PRE
(*):SOURCE:ICAO CARBON EMISSIONS CALCULATOR
CONFIGURATION-
388 F 14 J 97 W 55 M 303

Coupled with the sick A380 in Jo'burg, perhaps that is why a 6th A380 was pulled out of Madrid yesterday both for back-up and to prepare for the summer schedule starting next weekend!

Pilot37