Hi Michael,
After stripping out all useless parts, the program became very simple and I suspect that either I am doing something wrong or it’s already fixed, so I will just report it here:
cvx_begin sdp
variable P(2,2) symmetric
maximize trace(P)
subject to
P == eye(2);
cvx_end
The variable cvx_optval is 2 on MATLAB and 1 on Octave. Let me know if I should open a ticket for it.