The channel needs a little amoun locked on each side to act as a reserve, a good faith bond of sorts.

When an LSP opens a channel to your node, they can decide to push that amount to your side or not. If they don't, the first liquidity to come in will be used to fill up that reserve, and you won't be able to move it.

To fix the issue, send yourself some sats from another wallet. Once that reserve gets filled up, your channel will be fully operational.