Your LOS is correct. See the quote below from the TRID Official Interpretation:
12 CFR Part 1026, Appendix I, Official Interpretations, 37(a)(10-3
3. Periods not in whole years.
i. Terms of 24 months or more. For product types and features that have introductory periods or adjustment periods that do not equate to a number of whole years, if the period is a number of months that is 24 or greater and does not equate to a whole number of years, §1026.37(a)(10) requires disclosure of the whole number of years followed by a decimal point with the remaining months rounded to two places. For example, if the loan product is an adjustable rate with an introductory period of 30 months that adjusts every year thereafter, the creditor would be required to disclose ‘‘2.5/1 Adjustable Rate.’’ If the introductory period were 31 months, the required disclosure would be 2.58/1 Adjustable Rate.’’
ii. Terms of less than 24 months. For product types and features that have introductory periods or adjustment periods that do not equate to a number of whole years, if the period is less than 24 months, §1026.37(a)(10) requires disclosure of the number of months, followed by the designation ‘‘mo.’’ For example, if the product type is an adjustable rate with an 18-month introductory period that adjusts every 18 months starting in the 19th month, the required disclosure would be ‘‘18 mo./18mo. Adjustable Rate.’’
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Just my opinion, I could be wrong. - Dennis Miller