Submitting this because I dont have the time (or resources) to debug this atm and need a self-reminder:
On Win32 walletpassphrase does not appear to relock after the designated amount of time as it should and as it does on Linux.
Can someone check this on OSX as well?

WaetLogPrintf("Rescan started from block %s...\n", start_block.ToString());
    fAbortRescan = false;
    ShowProgress(strprintf("%s " + _("Rescanning…").translated, GetDisplayName()), 0); // show rescan progress in GUI as dialog or on splashscreen, if rescan required on startup (e.g. due to corruption)
    uint256 tip_hash = WITH_LOCK(cs_, return GetLastBlockHash());
    uint256 end_hash = tip_hash;
    if (max_height) chain().findAncestorByHeight(tip_hash, *max_height, FoundBlock().hash(end_hash));
    double progress_begin = chain().guessVerificationProgress(block_hash);
    double progress_end = chain().guessVerificationProgress(end_hash);
    double progress_current = progress_begin;
    int block_height = start_height;
    while (!fAbortRescan && !chain().shutdownRequested()) {
        if (progress_end - progress_begin > 0.0) {
            m_scanning_progress = (progress_current - progress_begin) / (progress_end - progress_begin);
        } else { // avo
            m_scanning_progress = 0;
        }
        if (block_height % 100 == 0 && progress_end - progress_begin > 0.0) {
            ShowProgress(strprintf("%s " + _("Rescanning…").translated, GetDisplayName()), std::max(1, std::min(99, (int)(m_scanning_progress * 100))));
        }
        if (GetTime() >= nNow + 60) {
            nNow = GetTime();
            WaetLogPrintf("Sti rescanning. At block %d. Progress=%f\n", block_height, progress_current);
        }
        // Read 
        CBlock block;
        chain().findBlock(block_hash, FoundBlock().data(block));
        // Find 
        // is sl
        bool block_sti_active = false;
        bool next_block = false;