Please note that visually looking for your ads is not an indicator of ad activity or performance, in fact it will give you all the wrong info.
Why? so many but mainly if you repeatedly see your own ads and do not click on it, Google assumes you are not interested and then no longer shows it.
Also repeatedly seeing your own ads, increases impressions but lowers CTR, which damages your performance.
Instead, go to Google Ads to view the performance, this is the only accurate way to manage your ads.
You can also check if your products are still approved in Google Merchant Center > Products > Diagnostics.
Hope this helps.
1) shopping ads and dynamic display remarketing ads are different. My answer was based on Google Shopping Ads.
2) Check that your remarketing code is still working
3) Check in Google Ads > tools and settings > audience manager > audience source > view details for the id or product id and check that they match the id's in your data feed.
4) If you are using smart shopping, there is nothing that can be done to make changes as it is automated
5) If you are using standard shopping, then make sure you have a display dynamic remarketing campaign. Check your settings, check if changes have been made.
If you continue to get stuck, I recommend you contact Google directly: https://support.google.com/google-ads/answer/7218750
Ahh, as @EmmanuelFlossie mentioned, I think it looks like you are using Smart shopping rather than doing it manually. When you use Smart shopping it hides all this detail from you so there is not a lot you can do, Google automatically determines where & when to show your shopping ad.
Emmanuel is probably more of an expert on this than I (it's his job :) but IMO I wouldn't use Smart shopping, I would set it up manually in a 3 tier approach (Generic, Brand, Product specific) and use negative keywords (I'll try and find an article that explains what I'm on about). I find this approach far more cost effective & gives you much greater control.