Hi,
[I am not an expert, but I have saved and reloaded Bert models].
What commands are you using to save and reload your model?   Are you saving just the BERT weights, or your custom dropout and linear layers too?
Do you get any error messages on reloading?   Do you get any error messages when you try to run your second classification task (or does it just go on in an infinite loop)?
Have you tried running your second task immediately after your first task (without doing a save and reload)?  Does it work?
[Silly questions] How do you know your first task has “worked”?  Are you using BertModel, and have you considered using BertForSequenceClassification?   When you train, are you updating the BERT weights, or have you frozen them?