Hi Dan,
There have been quite a few changes to delay balancing since R2017b. I recommend looking over our recent release notes.
One potential cause for the delay balancing error is a change to an option called PreserveDesignDelays in R2023b. This option was off by default, and I've seen many users turn it on in past releases. The option used to only preserve deisgn delays when using Distributed Pipelining, but now it also controls whether or not HDL Coder can leverage design delay to offset latency introduced by blocks and optimizations. The option has been renamed to AllowDelayDistribution, and it is on by default (option is inverse of prior option). If you had PreserveDesignDelays=on in your model, it will now show as AllowDelayDistribution=off in the same model in R2023b.
In addition to this change, there is also an improved Delay Balancing Optimization Report (also mentioned in the release notes). This report now gives detailed information on if delay absorption happened as well as what could have prevented it. This report is also directly linked in the delay balancing error message regarding feedback loops after that first sentence you quoted to help give contextual help when encountering these errors. Have you tried looking at it?
