Know-How Exchange : Advertising/PR

Fairly new to LinkedIn ads but as I understand, you need 300 matched contacts to run a targeted campaign. I've uploaded a list of 335 contacts and gotten a 90% + match rate which should put me over the threshold (335 * 0,9 =301,5), however, LinkedIn says my audience is too small to launch a campaign. Spoke to support about this and they told me some users may have privacy settings that keep them from being targeted, which could be putting me below the 300 mark. Obviously that is annoying since these settings aren't visible on my end, but what experiences to people have with this? Or does anyone know what % of users have settings like this? Ive uploaded lists of 1000 people before and that worked fine, so what would you guys say the "practical" minimum size is for uploaded lists? Would be sad to upload a list of 400 if 40% have privacy settings which would put me below 300, so how many people do you guys have as a minimum to get a list to work? Thank you!