Error importing data from .CSV file

Hello,

I currently have a matlab script, which calls a function that reads through a series of .csv files and pulls specified information [Below is code for function.m]. The matlab code will work with archived .csv files, but won't work with newly generated .csv files or recently updated/saved .csv files and am unsure why. See code below for function:

function [data] = readData(fileName)
%UNTITLED Summary of this function goes here
%   Detailed explanation goes here

colNames = ''; pids = '';
fid = fopen(fileName);
readColNames = true;
readPIDs = false;
lineCount = 0;
W1flag = false;
dataComing = false;
while ~feof(fid)    
    currLine = strtrim(fgetl(fid));
    lineCount = lineCount + 1;
    
    % catch first line without W1 after detection of lines with W1
    if ~startsWith(currLine,'W1') && W1flag
        break
    end
    
    % catch first line containing W1
    if startsWith(currLine,',W1')
        W1flag = true;
    end
        
    % detects when mnemonics begin
    if startsWith(currLine,',T')
        readColNames = false;
        readPIDs = true;                
    end
    % assumes files starts with listing of column names (actual PIDs)
    if readColNames
        colNames = [colNames, currLine];
    end
    
    if readPIDs && ~W1flag
        pids = [pids, currLine];
    end    
end
fclose(fid);

colNames = strrep(colNames,'/','_');
colNames = strsplit(colNames,',');

% remove duplicates
[cols, ind] = unique(colNames(2:end));
colNames = [colNames{1} colNames(ind+1)];
ind = [1 ind(:)'+1];

pids = strsplit(pids,',');
pids{1} = 'Date';
pids = pids(ind);

numHeaderLines = lineCount - 1;
lineCount = 0;

tic
tempDataFile = 'data_temp.txt';
fid_temp = fopen(tempDataFile,'w+');
fid = fopen(fileName,'r');
while ~feof(fid)    
    currLine = strtrim(fgetl(fid));
    lineCount = lineCount + 1;
    
    if (lineCount > numHeaderLines)
        currLine = regexprep(currLine,'(\d[+-])(\d)','$1e$2');
        fprintf(fid_temp,[currLine,'\n']);
    end
end
fclose(fid);
fclose(fid_temp);
toc

% clear formatSpec
% formatSpec = '%D';
% for k = 1:numel(pids)-1
%    formatSpec = [formatSpec ' %g']; 
% end
% fid = fopen(fileName);
% data = textscan(fid,formatSpec,'Delimiter',',','HeaderLines',lineCount-1);
% fclose(fid);

opts = detectImportOptions(tempDataFile);
% data = readtable(fileName,'HeaderLines',lineCount-1,'ExpChars',' ','Delimiter',',');
data = readtable(tempDataFile,opts);
data = data(:,ind);

data.Properties.VariableNames = colNames;
data.Properties.VariableDescriptions = pids;
data.Date_Time = datetime(data.Date_Time,'InputFormat','MM/dd/yyyy HH:mm:ss.SSS');
data(1:10,:)

% data.Properties.Description = pids;
% mid = floor(size(data,1)/2);
% data(mid-10:mid+10,:)
delete(tempDataFile)
end

The error I get, is as follows:

Index exceeds the number of array elements (7).
Error in readData (line 52)
pids = pids(ind);
Error in Procedure_1 (line 29)
    data = readData(currFile); 

For instance, the code will break if I take a .csv file that originally worked with the code and then... file > save > close.. resulting in the matlab code breaking. I'm very confused how this can be.

Note: The archived .csv files I'm working with are only from 2019, so they're still new.

Thanks for the help!