We employ resonant soft x-ray diffraction (RSXD) to isolate the signal from the CE-type antiferromagnetic phase of (La,Pr)_1-xCa_xMnO₃ (with x ≈ 3/8), and follow only this phase through the known phases of the material in the B-T phase diagram. This material is known to exhibit a range of electronic ordering phenomena, most notably a metal-insulator transition (associated with colossal magnetoresistance) and phase separation between the antiferromagnetic phase and a ferromagnetic phase. Bulk magnetization measurements under the same B-T conditions were also conducted, giving a full picture of both phases for direct side-by-side comparison. The comparison specifically focuses on the metal-insulator transition. Upon magnetic field ramping to this transition, we find that the CE-type order undergoes a sharp quench at high temperatures (above phase coexistence temperatures) but that at lower temperatures, where the CE order is metastable, the transition broadens significantly. At the lowest temperatures, where a spin glass-type phase is expected, a slow annihilation of remanent CE domains is observed. Finally, a refined phase diagram is presented.