Sometimes, ideas flow and sometimes they don’t. When working on a difficult problem, it’s really important to ensure you actually get the chance to work on it. Turn off notifications and other distractions and really think.
Going to another room & thinking on paper can help.
Better yet, go for a walk.
Talk to a colleague/peer - even if they can’t offer advice, just talking the problem through will often help shake a solution out from hiding.
You can’t force a creative leap. So if you’re still at a loose end, take a break, do something else & come back later or the following day.
Eventually, your subconscious will deliver!