How can I transfer back to IRR from the "Try One" program?

I enlisted with a 4 x 4 contract with active duty, and completed my active obligation with an honorable discharge in 2018. A year goes by a 79V comes to me and offers me to do the "Try One" program. She assures me that if I do not like it I can just switch back to IRR, no questions asked since all it took was a 4187 to put me in. Long story short, I want to go back to the IRR because of personal, financial reasons but the unit is telling me that I "may or may not be able to go back" depending on the brigade or command. What the hell? Did I get scammed or something? I've been looking up regulations and I've yet to find anything on this program except for the fact that it is on the Army Reserves website but the details are very vague. It doesn't seem fair that the Army has this program to trick IRR Soldiers into the USAR and locks them in at the commander's discretion. The only reason I signed the 4187 because it's a "trial program" and I was told if I didn't like it, then I could go back. What are my options here?