Do you think the disulfide bond will remain intact?
Yeah I think so. Im not really into this kind of chemistry but my wife was breaking some disulfide bonds and afaik it required reducing agents such as PPh3
Also, if its solid phase chemistry, dont forget TFA cleaves your product from resin. Dont know what are exact procedures in your group but ours "SPSists" cleave with TFA, filter the residual resin, wash few times with DCM and purify on HPLC or with common collumn chromatography.
Futhermore, based on your first post and description of the procedure "nothing happened" is quite broad steatement. Is there no reaction? Or no precipitation by ether? You might also be getting some intramolecular amidation. Seems likely since it formes 6-membered diketopiperazine