I would recommend hiring your own expert to get through humps like this. You're going to save your time, resolve an issue quickly, also you'll know how to do it

I would recommend hiring your own expert to get through humps like this. You're going to save your time, resolve an issue quickly, also you'll know how to do it next time, and you still bill your client for the work (probably less than you taking the time to figure it out). Just invoice them normally by the way, typically you don't have to advertise you hired outside help unless your contact specifies or restricts it. I can't justify charing my clients for large chunks of time figuring something out. Everyone runs in to issues that can take some time figuring out. I will invoice for that. If it's something challenging they requested reach out to them and say this is taking more time than I expected, can you ok increasing this to 8 to 16 more hours? Also taking a break from a problem and coming back to it after a walk, shower or even overnight often times the solution will be there when you start back on it. Good luck tackling this issue.