My DelayTime isn't changing correctly with my LFO

    for (auto i = totalNumInputChannels; i < totalNumOutputChannels; ++i)
        buffer.clear (i, 0, buffer.getNumSamples());

    for  (int channel = 0;  channel < totalNumInputChannels; ++channel)
    {   //Set a pointer to read from the main audio buffer. 
        auto* channelData = buffer.getWritePointer(channel);
        //initialize a pointer to read past audio samples at audio. 
        auto* ringBuffptr = mRingBuf.getReadPointer(channel);
        int  readIndx; // the index of the samples being read from the buffer. 
        readIndx = mRingBufferWriteIdx;
        //Copy over the block of audio from the main audio buffer to our ring buffer.
        mRingBuf.copyFrom(channel, mRingBufferWriteIdx, buffer, channel, 0, buffer.getNumSamples());
        int delayInSeconds = (3 * mSampleRate);
        for (int i = 0; i < buffer.getNumSamples(); ++i, ++mRingBufferWriteIdx)
            // advance the modulator signal angle by one increment for the next sample
        float LFOsample = std::sin(mCurrentPhase);
        //Scale the samples by 5ms of samples
        LFOsample *= roundToInt(0.02 * mSampleRate);
        LFOsample += roundToInt(0.005 * mSampleRate);
        LFOsample *= mLFODepth;

        //step back however many samples of audio. 
        readIndx = mRingBufferWriteIdx - LFOsample;

        //wrap the pointer back to the begining of the buffer.
        //This is a safety check. 
        if (readIndx < 0)
            readIndx += mRingBufferSize;

            readIndx %= mRingBufferSize;
            //increment the readIndex to read the delayed samples into the main audio buffer.
            channelData[i] = ringBuffptr[readIndx++];
    // advance mCurrentAngle by N steps
    mCurrentPhase += mPhaseChange* buffer.getNumSamples();
    mCurrentPhase = fmod(mCurrentPhase, 2 * MathConstants<double>::pi);

the LFO phase should be updated sample by sample and not once per block. You actually update it numChannels times, each time you’ve processed a channel.
Do you update your ring buffers write index? I am missing the two-part write there, as it might wrap after some time.