Do you receive the message "transaction processing", no reaction or another error message?
The following solutions seemed to have worked for people facing issues:
1) Make sure MetaMask has permission to read and change all your data on the website you visit.
2) Clear the cache of your browser, log out from MetaMask and start again (if it pops on MetaMask and does not confirm on your ledger, it is a cache issue).
3) Reboot your device (phone, tablet, desktop).
4) Make sure MetaMask is set on either BSC (How to connect to BSC network on MetaMask) or Ethereum Mainnet (on top when you open MetaMask).
5) Wait for the transaction to be approved, which might take between 10-40 minutes (it also depends how much fee (gas) you paid).
6) Change the web browser (We recommend using Firefox or Brave).
7) Connect your wallet to Uniswap or Balancer first, and check if transactions work on their platform (if not, continue with their support service).
8) Provide liquidity on the LP from Balancer or Uniswap. Then connect to our UI and stake your LP tokens.
9) Try Incognito Mode
10) Switch to another network in MetaMask and come back to the original network.