equation solving – Solve::units: Solve was unable to determine the units of quantities that appear in the input

I’d like to solve the following two equations for P. But I’m getting “Solve was unable to determine the units of quantities that appear in the input.”. Any suggestions on what could be the cause for this?

Clear("Global`*") ;
Solve({T^4 == ((1 - A) (1 - P) Subscript(R, s)^2 Subscript(T, 
    eff)^4)/(2 a^2), Subscript((CapitalDelta)F, SE)/F == (!(
*SubsuperscriptBox((R), (p), (2)) * 
*SubscriptBox((T), (day))))/(
   Subscript(R, s )* Subscript(T, eff))}, {P, Subscript(T, 
  eff)}, Reals)