Sorry I can't reproduce
SQL> CREATE TABLE "TMP_CONTA_ERRO"
2 ( "COER_DT" DATE NOT NULL ENABLE,
3 "COER_SESSION" VARCHAR2(30) NOT NULL ENABLE,
4 "COER_COPA_SQ" NUMBER NOT NULL ENABLE,
5 "COER_LOGIN" VARCHAR2(60) NOT NULL ENABLE,
6 "COER_ST_PENDENCIA_IMPORTADA" VARCHAR2(1),
7 "COER_TP_ADMISSAO" VARCHAR2(2),
8 CONSTRAINT "COER_PK" PRIMARY KEY ("COER_DT", "COER_SESSION", "COER_COPA_SQ")
9 USING INDEX PCTFREE 10 INITRANS 5 MAXTRANS 255 COMPUTE STATISTICS
10 STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
11 PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
12 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
13 TABLESPACE "USERS" ENABLE
14 --,
15 --CONSTRAINT "COER_COPA_FK" FOREIGN KEY ("COER_COPA_SQ")
16 -- REFERENCES "SIFH"."CPA_CONTA_PACIENTE" ("COPA_SQ") ENABLE
17 ) SEGMENT CREATION IMMEDIATE
18 PCTFREE 10 PCTUSED 40 INITRANS 5 MAXTRANS 255
19 NOCOMPRESS LOGGING
20 STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
21 PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
22 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
23 TABLESPACE "USERS"
24 /
Table created.
SQL>
SQL>
SQL> INSERT INTO tmp_conta_erro (coer_dt, coer_session, coer_copa_sq, coer_login) VALUES (TRUNC (SYSDATE), '1', 7693605, 'TEST');
1 row created.
SQL> INSERT INTO tmp_conta_erro (coer_dt, coer_session, coer_copa_sq, coer_login) VALUES (TRUNC (SYSDATE), 'A', 7693605, 'TEST');
1 row created.
Next step would be look at dropping-recreating it and seeing if the issues continues. Keep us posted.