There is no creation-redemption mechanism, so nothing forces price toward nav. Discounts of 8% to 15% are common and can persist for years; premiums appear where a manager or a payout is fashionable. Many closed-end funds also use leverage, which amplifies both the NAV move and the discount swing.
Distributions are the usual trap. A headline 11% yield is often part return-of-capital, which is simply the fund handing back your own money while the NAV erodes.
Example: NAV $18.40, market price $16.10, a 12.5% discount. Buying at the discount means $1.00 of assets costs $0.875, and $0.90 of annual distributions is a 5.6% yield on NAV but 5.6 / 0.875 = 6.4% on your price.
Related: nav, premium-discount-to-nav, return-of-capital, etf, expense-ratio