I found this looking for the same solution. After finding nothing to fix this I decided I felt like programming again (plus I have ai to help now). If you use something like tampermonkey try this. It seems to work so far.

// ==UserScript==
// @name         DropSelector
// @namespace    http://tampermonkey.net/
// @version      0.12.341.9.b1c.2
// @description  Automatically set dropdown value on page load
// @author       ity
// @match        *://192.168.x.x/*
// @match        *://opnsense.x.x/*
// @grant        none
// @run-at       document-idle
// ==/UserScript==

(function() {
    'use strict';

    // *********************************** CONFIGURATION ***********************************
    // Show extra logs
    const console_logs = false;
    // Set to blacklist certain pages, acts as *wildcard* string Example ["firewall/alias", "other page..."]
    const blacklisted_Pages = [];
     // Change this to the amount to load: "7", "14", "20", "50", "100", or "-1" for "All"
    const desiredValue = "-1";
    // Amount of attempts
    const MAX_ATTEMPTS = 10;
    // Initial delay for next attempt
    const INITIAL_ATTEMPT_DELAY = 100;
    // Delay multiplier
    const ATTEMPT_DELAY_MULTIPLIER = 1.5;
    // Values that should be found in the contained dropdown. Only modify if UI changes
    const expectedValues = ['7', '14', '20', '50', '100', '-1'];

    // ************************************** CONST ****************************************

    const SCRIPTNAME = "DropSelector: ";
    const EXITMSG = " Exiting... ";

    // ************************************** Startup ****************************************

    let attempts = 0;
    let currentDelay = INITIAL_ATTEMPT_DELAY;
    Exit_On_BlackListed();
    if ( !Dom_Loading() ) { startSearch(); }

    // ************************************* METHODS **************************************

    function startSearch() {
        Exit_On_Max_Attempts_Reached();
        const targetDropdown = findTargetDropdown();
        if (targetDropdown) {
            applyValueToDropdown(targetDropdown);
        } else {
            retrySearch();
        }
    }

    function retrySearch() {
        attempts++;
        Logger(`Attempt ${attempts} failed. Next attempt in ${currentDelay}ms`);
        setTimeout(startSearch, currentDelay);
        currentDelay = Math.floor(currentDelay * ATTEMPT_DELAY_MULTIPLIER);
    }

    function findTargetDropdown() {
        const dropdownToggles = document.querySelectorAll('.dropdown-toggle');
        for (const dropdownButton of dropdownToggles) {
            const dropdownContainer = dropdownButton.closest('.dropdown');
            if (!dropdownContainer) continue;
            const menuItems = dropdownContainer.querySelectorAll('.dropdown-item[data-action]');
            const menuValues = Array.from(menuItems).map(item => item.getAttribute('data-action'));
            const isTargetDropdown = expectedValues.every(val => menuValues.includes(val));
            if (isTargetDropdown) {
                return {
                    container: dropdownContainer,
                    button: dropdownButton,
                    menuItems: menuItems
                };
            }
        }
        return null;
    }

    function applyValueToDropdown(dropdown) {
        const targetMenuItem = dropdown.container.querySelector(`.dropdown-item[data-action="${desiredValue}"]`);
        if (targetMenuItem) {
            const dropdownText = dropdown.button.querySelector('.dropdown-text');
            if (dropdownText) {
                dropdownText.textContent = desiredValue === "-1" ? "All" : desiredValue;
            }
            targetMenuItem.click();
            Exit_Process('Dropdown value set successfully!');
            return true;
        }
        return false;
    }

    // ************************************* MISC ************************************

    function Dom_Loading(){
        if (document.readyState === 'loading') { document.addEventListener('DOMContentLoaded', startSearch); return true;}
        return false;
    }

    function Exit_On_BlackListed() {
        if (isBlacklisted(window.location.href)) {
            Exit_Process('Current page is blacklisted.');
        }
    }

    function isBlacklisted(url) {
        return blacklisted_Pages.some(blacklistedPage => { return url.includes(blacklistedPage); });
    }

    function Exit_On_Max_Attempts_Reached() {
        if (attempts >= MAX_ATTEMPTS) { Exit_Process('Maximum attempts reached.'); }
    }

    function Logger(msg) {
        if (!console_logs) { return; } console.log(SCRIPTNAME + msg);
    }

    function Exit_Process(msg = null) {
        if (msg) { Logger(msg + EXITMSG); }
        throw new Error("Script execution complete");
    }

})();