Add Exception is finicky
Since removing the SPI root cert, users are forced to add an exception when joining OFTC. Apart from that being undesirable on its own, some users have raised the issue that the process doesn't work consistently (or even at all). It "works for me" but the number of reports leads me to believe we should investigate further.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information