If you can withdraw less from what you have in the ‘Free funds’, then some of the funds are blocked for one of these reasons:
You received free fractional shares
The value of such shares can be used for investments instantly, however, it will be available for withdrawal 30 days after receiving the stock. Check your Get free shares dashboard for the exact value of free fractional shares that may be locked.
You received cashback
If you received 1% cashback on your ISA deposits, it stays locked for 12 months.
You have open positions
Your funds may still be invested. To free up some cash for withdrawal, you need to close a position.
Your cash is in a pie
You need to withdraw the funds back to your account's free cash. Here is how. Then, you will be able to place a withdrawal.