There have been numerous attempts, in the last decades, to unravel the origin of the unexpectedly significant transverse single-spin asymmetry ($A_{N}$) observed in inclusive hadron productions at forward rapidities in transversely polarized $p^{\uparrow}$+$p$ collisions across various center-of-mass energies ($\sqrt{s}$). The theoretical frameworks that explain this puzzle include the twist-3 contributions in the collinear factorization framework, the transverse-momentum-dependent contributions from the initial-state quark and gluon Sivers functions, and/or final-state Collins fragmentation functions. Recent studies at STAR have also suggested that the prominent $A_{N}$ values may potentially arise from diffractive processes. We present detailed investigations into the $A_{N}$ for electromagnetic jets (EM-jets) produced in inclusive processes using the Forward Meson Spectrometer with transversely polarized $p^{\uparrow}$+ $p$ data at $\sqrt{s} =$ 200 GeV collected in 2015 at STAR. Additional studies are performed in order to isolate contributions from diffractive processes to the large inclusive $A_{N}$. However, the negative and non-zero $A_{N}$ is observed for EM-jets in diffractive processes, which can not prove that the large $A_{N}$ in inclusive processes might come from diffractive processes. Finally, we present the statistical projections of the $A_{N}$ for inclusive and diffractive EM-jets utilizing $p^{\uparrow}$+ $p$ data at $\sqrt{s} =$ 510 GeV collected in 2017 at STAR. This dataset provides complementary measurements at a high value of $\sqrt{s}$ with a substantial enhancement in statistical precision.