The clipper stays "クリップを保存中...(Saving clip...)" state until the timeout error occurs, and never start to sync on Firefox.
Webclipper for Chrome works for the same page, so it's the problem on Firefox Clipper.
Log:
クリッパーにエラーが発生しました
不明なエラーが発生しました。
undefined/undefined
Message did timeout
Evernote Web Clipper 7.13.1.1-fdf32c3 Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:79.0) Gecko/20100101 Firefox/79.0
Clipper core: 1.5.0-98592b5
Locale: ja
3978984 experiments status:
{
"SaveButtonPos_CLIPPER-1768": null,
"ClipTypeOrder_CLIPPER-1992": null
}