The investments were a failure, I have been writing off the expenses since the1970s without any questions.
CRA has explicitly named line 224 entries as "paper only" for filing purposes. The agency requires that the Form T1229 and your T5, T101, and T5013 slips be attached to your paper return. If you don't have these slips, you can include a statement instead. Here's the link from CRA for more details: https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/tax-return/completing-a-tax-return/deductions-credits-expenses/line-224-exploration-development-expenses.html