Question: Strange DifferentialAlgebra error from pdsolve

I'm receiving a very interesting error when attempting to solve a system of differntial equations:

{sqrt(2)*sqrt(F1(t))*diff(F2(t),t) = 0}:
% union {F3(t) = 0}:
pdsolve(%, {F1(t),F2(t),F3(t)});

When attempting to run this code, I get the following error:

Error, (in pdsolve/sys) invalid input: DifferentialAlgebra:-DifferentialRing expects value for keyword parameter blocks to be of type {undefined, Or(list({name, unknown, list({name,unknown})}),name,unknown)}, but received [F3, F2, _F1 = (NULL), F1 = [_F1, F1], _F2] 

Interestingly, removing the second line, or even the sqrt(2), allows the calculation to proceed correctly. It this a bug, or am I doing something wrong?

Thank you very much!

(I'm aware this would technically be a system of ODEs, not PDEs; my actual code includes additional partial derivatives. Additionally, dsolve appears to only generate a trivial solution in this case).