Fixes broken (*) formatting rules in Google Sheets. (*) Broken = range has been messed up by cut&paste. Paste this code in Tools/Script Editor.

gistfile1.txt

function onEdit(e) {
  checkAndFix();
}

/*
function onOpen() {
  var ui = SpreadsheetApp.getUi();
  // Or DocumentApp or FormApp.
  ui.createMenu('Custom Tools')
      .addItem('Check formatting rules', 'checkAndFix')
      .addToUi();
}
*/

function checkAndFix() {
  let sheet = SpreadsheetApp.getActiveSheet();
  if (sheet && hasBrokenRules(sheet)) fixBrokenRules(sheet);
}

function hasBrokenRules(sheet) {
  for(let rule of sheet.getConditionalFormatRules()) {
    if (rule.getRanges().length > 1) return true
  }
}

function fixBrokenRules(sheet) {
  // fix broken rules
    let newRules = [];
    let rule;
    let colMin, colMax, rowMin, rowMax;
    let ranges;
    for(let r1 of sheet.getConditionalFormatRules()) {
      rule = r1.copy();
      ranges = rule.getRanges();
      if (ranges.length > 1) {
        rowMin = colMin = Number.MAX_VALUE;
        rowMax = colMax = -1;

        for (let range of ranges) {
          if (range.getColumn() < colMin) colMin = range.getColumn();
          if (range.getLastColumn() > colMax) colMax = range.getLastColumn();
          if (range.getRow() < rowMin) rowMin = range.getRow();
          if (range.getLastRow() > rowMax) rowMax = range.getLastRow();
        }
        
        rule.setRanges([sheet.getRange(rowMin,colMin, rowMax-rowMin+1, colMax-colMin+1)]);
      } else {
        // rule with unique range: OK
        let range = rule.getRanges()[0];
        // BUT: a rule with 1x1 range should not be pushed (happens sometimes during cut&paste)
        if (range.getWidth() ==1 && range.getHeight() == 1) rule = null;
      }
      if (rule) newRules.push(rule);
      
    }
    sheet.setConditionalFormatRules(newRules);
}