Weird; assuming you've tried the below but just in case... from reddit

Download a bitcoin lighting wallet like Wallet of Satoshi

⚡️ Copy your LN URL address and paste it into your profile in the LN Address field/ln-06. "edit profile wiyh pencil icon"

Add zap invoice to a post:

🍊 Tap on receive and set any amount of sats on the invoice

☀️ Copy invoice LN URL and paste it in a post

Might vary depending what you're using (me:amethyst)

GL