I get the same error when converting to either EPUB or PDF, and I've never encountered it before. It happens only with this one ebook. All other Kindle files have converted fine, including the others from this series.
calibre, version 5.40.0
ERROR: KFX conversion failed: <p><b>Cannot convert A Practical Guide to Personal Finance (Practical Guide Series)</b><br><br>Exception('section c3W, $269 1004, story l40, $270 1093, $278 1091, $454 1090, $279 1044 unexpected hr found in table_row\nsection c3W, $269 1004, story l40, $270 1093, $278 1091, $454 1090, $279 1044 unexpected hr found in table_row\nsection c3W, $269 1004, story l40, $270 1093, $278 1091, $454 1090, $279 1059 unexpected hr found in table_row\nsection c3W, $269 1004, story l40, $270 1093, $278 1091, $454 1090, $279 1059 unexpected hr found in table_row\nsection c3W, $269 1004, story l40, $270 1093, $278 1091, $454 1090, $279 1077 unexpected hr found in table_row\nsection c3W, $269 1004, story l40, $270 1093, $278 1091, $454 1090, $279 1077 unexpected hr found in table_row\nsection cTR, $269 1703, story lTV, $270 1834, $278 1831, $454 1830, $279 1781 unexpected hr found in table_row\nsection cTR, $269 1703, story lTV, $270 1834, $278 1831, $454 1830, $279 1781 unexpected hr found in table_row\nsection cTR, $269 1703, story lTV, $270 1834, $278 1831, $454 1830, $279 1805 unexpected hr found in table_row\nsection cTR, $269 1703, story lTV, $270 1834, $278 1831, $454 1830, $279 1805 unexpected hr found in table_row\nsection cTR, $269 1703, story lTV, $270 1834, $278 1831, $454 1830, $279 1829 unexpected hr found in table_row\nsection cTR, $269 1703, story lTV, $270 1834, $278 1831, $454 1830, $279 1829 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2153, $454 2152, $279 2103 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2153, $454 2152, $279 2103 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2153, $454 2152, $279 2118 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2153, $454 2152, $279 2118 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2153, $454 2152, $279 2136 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2153, $454 2152, $279 2136 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2153, $454 2152, $279 2151 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2153, $454 2152, $279 2151 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2280, $454 2279, $279 2230 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2280, $454 2279, $279 2230 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2280, $454 2279, $279 2254 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2280, $454 2279, $279 2254 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2280, $454 2279, $279 2278 unexpected hr found in table_row\nsection c15M, $269 2084, story l15S, $278 2280, $454 2279, $279 2278 unexpected hr found in table_row')</p>