Effects added to the audio stems when I import them in another project

Hi Everyone,

I recorded new vocals in a new project using only the rough beat mix-down on one track as a reference for the singer. Then I bounced all the vocal tracks as separate files, imported them in the existing project where I created the beat and to my surprise all the vocal stems have some reverb added to them. I went up and down the project and there's no plug-in or send affecting them. I would think that I maybe made a mistake when I bounced the stems from the other project, but when I listen to them in the finder folder they are absolutely clean from any effect. I even re-bounced all the tracks making sure to by pass effects and plugins on the last window in the process and I got the same result.

Any idea?

Thanks in advance