An account freeze is a restriction placed on an account by the firm holding it, under which some or all activity stops while something is resolved. It is not one thing: a freeze can block payments out while trading continues, block trading while positions remain open, or block everything, and which of those applies is the first question rather than a detail.
The reasons fall into two groups that behave differently. Compliance reasons — an expired document, an unanswered request, a payment that did not match the account, an order from a competent authority — end when the underlying matter is closed, and in most of those cases the firm can say what is outstanding. Reasons involving a legal instruction or an active investigation may come with restrictions on what the firm is permitted to explain, which is why a freeze is sometimes accompanied by less information than a client expects rather than by evasion. The practical points are the same either way: open positions usually continue to move and to consume margin while an account is frozen, so a freeze is not a pause, and the route to resolving it is the firm's complaints procedure and the regulator behind it rather than the trading desk.
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Standard, raw, cent, swap-free, professional. What genuinely differs between the tiers, and the one reclassification that costs you protections.