Merging datasets in R results in incomplete string values

Question

I wanted to merge two datasets and the merging resulted in getting incomplete strings in a variable

# Librerias
```{r}
library(dplyr)
library(tidyr)
library(tidyverse)
library(readxl)
library(readr)
library(base)
library(stringr)
library(foreign)
library(forcats)
library(fs)
library(hablar)
library(openxlsx)
```
# Comercio CIIU
```{r}
# Mercancias
Catalogo_comercio_CIIU <- read_excel("Comercio/Catalogo comercio bienes CIIU.xlsx") %>%
  mutate(ACTIV4=CIIU)

CIIU_Exportaciones <- read_excel("Comercio/CIIU Exportaciones.xlsx") %>% 
  pivot_longer(cols = -...1, names_to = "Period", values_to = "Valor") %>% 
  mutate(Flujo="Exportaciones")

CIIU_Importaciones <- read_excel("Comercio/CIIU Importaciones.xlsx") %>% 
  pivot_longer(cols = -...1, names_to = "Period", values_to = "Valor") %>% 
  mutate(Flujo="Importaciones")

Length<- CIIU_Exportaciones %>% group_by(...1) %>% 
  summarise(Obs=n())
Length<- Length$Obs[[1]] %>% 
  as.numeric() %>% 
  as.vector()

# Mensual
Comercio_bienes_mensual <- rbind(CIIU_Importaciones, CIIU_Exportaciones) %>% 
  rename(Actividad="...1") %>% group_by(Flujo, Actividad) %>% 
  mutate(Fecha=seq(from=as.Date("1994-01-01"), by="month", length.out=Length)) %>% 
  mutate(Year=str_sub(Fecha, 1L,4L), Mes=str_sub(Fecha, 6L,7L)) %>% 
  group_by(Flujo, Actividad, Year) %>% 
  mutate(Acumulado=cumsum(Valor)) %>% 
  group_by(Flujo, Actividad) %>% 
  mutate( C_acumulado= Acumulado-lag(Acumulado, n=12L), TC_acumulado=Acumulado/lag(Acumulado, n=12L)-1 ) %>% 
  merge(Catalogo_comercio_CIIU,  by="Actividad") %>% 
  select(-Grupo,-Detalle,-Categoria1,-Categoria2)
```

This is the catalogue I want to merge

This is how the merging turned out (incomplete string)

I am a beginner so I don't really know what to try