@Zac_Spitzer I’m sorry you lost that much time over this!
In older ACF version, ACF did buffer the output even you where inside a silent block and in case of an exception or abort still did output it.
In our opinion this was an invalid behaviour, but still we did follow ACF on this, but we did make it possible to configure it differently in the admin. Also because that behaviour is a big waste of memory and time!
Based on the ticket above we have found out that ACF has changed that behaviour and because of that we changed the DEFAULT behaviour of Lucee as well to be compatible to ACF.
That is the problem of nearly every incompatibility fix, making something more compatible to ACF, could possible break compatibility to older Lucee versions.
Should we reverse that change and keep the default behaviour of older version and wait with that change for Lucee 5.3?
In any case we have to make sure we clearly communicate that change with the release of 5.2.6 or 5.3. @IamSigmund can you please make sure of this i will provide you the necessary info.