I've been tackling this issue for more than three hours convinced that the problem lies within the imported data. To my surprise it turns out that the Lucid chart is unable to add links between shapes even though the link information is present in the CSV.
I manually built a chart with multiple lines and exported it as CSV however my attempts to import that same CSV and recreate the chart have been met with failure.
In need of assistance as soon as possible. If anyone has encountered a similar issue or knows a workaround your guidance would be greatly appreciated! Thank you in advance!