Latency issues in pro tools

Having extreme latency issues in using Neural DSP plug ins with pro tools.
Long time Kemper user and there are no real issues with that using the spdif/optical through my UA Apollo. Have used low latency mode in Logic with the DSP plug ins and they now work within Logic.
In ProTools I plug into the Apollo and use line 1 input which works fine s a standalone application for rehearsals etc. In proTools I have reduced buffer to 128 but to little effect. When I use the low latency input on ProTools found under the options tab it bypasses the DSP plug in and won’t let me use it. any ideas would be a real boon. I’m using an iMac with plenty of Ram.