Ask HN: Pinterest/Reddit ad stat shows clicks but GA doesn't

Hello, Anybody have experience with Pinterest/Reddit ad conversions? I'm trying certain subreddits and Pinterest with a pin for a proptech idea I'm testing [1]. The PI/Reddit ad boards show clicks coming in, but my Google Analytics don't show them/shows the duration of visit as 0 secs. I wonder if these are bots or actual users? Anybody faced a similar issue? Thanks in advance!

[1]https://www.pinterest.co.uk/pin/834854849673042838/