Hey @andreas.w and @deanishe I think I am having the same problem as AV8RDude with authentication.
Here are my logs, there is nothing weird happening that I see. Note, I changed my real client_id to 'myClientID'.
[13:09:13.871] Search Raindrop.io[Script Filter] Queuing argument '(null)'
[13:09:13.960] Search Raindrop.io[Script Filter] Script with argv '(null)' finished
[13:09:13.961] Search Raindrop.io[Script Filter] {"items":[{"arg":"https:\/\/raindrop.io\/oauth\/authorize?redirect_uri=http%3A%2F%2F127.0.0.1%3A11038&client_id=myClientID","subtitle":"Press enter to authenticate now","title":"You are not authenticated with Raindrop.io","valid":true}]}
[13:09:16.259] Search Raindrop.io[Script Filter] Processing complete
[13:09:16.263] Search Raindrop.io[Script Filter] Passing output 'https://raindrop.io/oauth/authorize?redirect_uri=http%3A%2F%2F127.0.0.1%3A11038&client_id=myClientID' to Conditional
[13:09:16.264] Search Raindrop.io[Conditional] Processing complete
[13:09:16.264] Search Raindrop.io[Conditional] Passing output 'https://raindrop.io/oauth/authorize?redirect_uri=http%3A%2F%2F127.0.0.1%3A11038&client_id=myClientID' to Conditional
[13:09:16.265] Search Raindrop.io[Conditional] Processing complete
[13:09:16.265] Search Raindrop.io[Conditional] Passing output 'https://raindrop.io/oauth/authorize?redirect_uri=http%3A%2F%2F127.0.0.1%3A11038&client_id=myClientID' to Arg and Vars
[13:09:16.266] Search Raindrop.io[Arg and Vars] Processing complete
[13:09:16.266] Search Raindrop.io[Arg and Vars] Passing output 'https://raindrop.io/oauth/authorize?redirect_uri=http%3A%2F%2F127.0.0.1%3A11038&client_id=myClientID' to Run Script
[13:09:16.927] Search Raindrop.io[Run Script] Processing complete
[13:09:16.930] Search Raindrop.io[Run Script] Passing output 'Alfred Preferences
' to Arg and Vars
[13:09:16.931] Search Raindrop.io[Arg and Vars] Processing complete
[13:09:16.932] Search Raindrop.io[Arg and Vars] Passing output 'Alfred Preferences
' to Conditional
[13:09:16.932] Search Raindrop.io[Conditional] Processing complete
[13:09:16.933] Search Raindrop.io[Conditional] Passing output 'Alfred Preferences
' to Open URL